Delkevic exhaust

[powerslave]

  Tried a search and didn't find much. Anyone running them? Opinions?

[98valk]

I contacted the seller on ebay? they said the header pipes have a larger ID than OEM, so there will be a HP increase.

[MarkT]

Nope.  Sorry. That's true only with a caveat. There will be a torque decrease and HP up only at high RPMs.  Of course the seller says that.  Smaller headers make more torque, especially at lower rpm's, at the expense of high hp at high rpm's.  And produce more scavenging to draw out the exhaust gas and increase the fuel/air charge. And provide quicker throttle response.  Large headers make more hp at higher rpm's at the expense of torque down low. To me, that means the stock headers are more suited to a street bike, while large pipe headers are better if you are going to race.  BTW I don't much care anymore on having a lot of business - no longer promoting the exhaust mods, just doing them as the orders come in. OK with that rate as I'm taking it easy now.

See http://www.valkyrieforum.com/bbs/index.php/topic,98222.msg976485.html#msg976485

[98valk]

Nope.  Sorry. That's true only with a caveat. There will be a torque decrease and HP up only at high RPMs.  Of course the seller says that.  Smaller headers make more torque, especially at lower rpm's, at the expense of high hp at high rpm's.  And produce more scavenging to draw out the exhaust gas and increase the fuel/air charge. And provide quicker throttle response.  Large headers make more hp at higher rpm's at the expense of torque down low. To me, that means the stock headers are more suited to a street bike, while large pipe headers are better if you are going to race.  BTW I don't much care anymore on having a lot of business - no longer promoting the exhaust mods, just doing them as the orders come in. OK with that rate as I'm taking it easy now.

See http://www.valkyrieforum.com/bbs/index.php/topic,98222.msg976485.html#msg976485

still talking in laymans terms? u are making general statement/s and really don't know what your talking about. u don't design exhaust systems, u only changed mufflers. go read people who do design and have the dyno reports. like everything there is a balance and the OEM headers are undersized even for the street and the top rpms and HP the engine is capable per its cams and carbs.
stop trying to protect your muffler change out business, by posting short sighted info.
good bye, your on ignore.

[MarkT]

Whatever.  Still beating the drum from your ignorent viewpoint.  The headers I use are designed by Honda engineers for a street bike who clearly know what they are doing.  Read the article I linked. Bet you can't stop beating your drum. Like I said - I know what I'm talking about been doing this almost 20 years.  You clearly don't.  And unlike you I support this club with money and prizes at Inzanes. As well as vets orgs.

[rocketray]

I have a set of Viking headers and the seat of my pants agree's w/Mark--I do seem to have to downshift more instead of just twisting the throttle---it has been  fun doing that and the open header sounds great but...torque is better on the street as Mark says...I don't understand why some members of this forum cannot have a civil discussion..they are right and that's the end---and Mark has built 1,500 exhausts!!!..he easily is the authority on our bikes..wow..here is to more  civil discourse..peace/love and harmony

[Bigwolf]

I know nothing about the delkevic exhaust system other than what I can read on their website.  They look like a nice set of exhaust and I like that they are stainless mufflers.

However, IMHO, you would do well to pay attention to Mark's words.  I don't know why Mark has decided to share the science of exhaust systems with everyone that reads these exhaust threads.  Most of that science is way over the head of most people and therefore will always be denied and rebuked.  I have spent a lifetime around race tracks.  I have seen first hand that it is a rare person that understands how an internal combustion engine actually breathes.  Bigger is not always better.  You can actually kill the power of an engine just by making the exhaust the wrong diameter or length.  If you are building a blower engine, the larger diameter primary pipes will work well.  They will not help a normally aspirated stock engine.  Now with a full modification like Attic Rat provides, you might see some benefit with larger primary exhaust, but I would ask him about that while he was doing the mods.

Best of luck to you,
Bigwolf

[dago mooserider]

Well, based on my dyno sheets.... you're both right... I have attic rat mods to my bike so, that changes it a bit. I dyno'ed with mark-t exhaust with crossover (factory headers) and then again with Vikings (larger headers) no jetting change. The mark t exhaust is the slight torque winner  until about 3800 rpm. Then the Vikings take over with 9 more horse power at difference at 6500 and 6 more ft-lbs at 4400. I wanted max HP and regularly rev it past 7k rpm. I too, know nothing about delkevic but it does look nice.

[The emperor has no clothes]

Well, based on my dyno sheets.... you're both right... I have attic rat mods to my bike so, that changes it a bit. I dyno'ed with mark-t exhaust with crossover (factory headers) and then again with Vikings (larger headers) no jetting change. The mark t exhaust is the slight torque winner  until about 3800 rpm. Then the Vikings take over with 9 more horse power at difference at 6500 and 6 more ft-lbs at 4400. I wanted max HP and regularly rev it past 7k rpm. I too, know nothing about delkevic but it does look nice.

Have you over ridden the rev limiter ?

[98valk]

Well, based on my dyno sheets.... you're both right... I have attic rat mods to my bike so, that changes it a bit. I dyno'ed with mark-t exhaust with crossover (factory headers) and then again with Vikings (larger headers) no jetting change. The mark t exhaust is the slight torque winner  until about 3800 rpm. Then the Vikings take over with 9 more horse power at difference at 6500 and 6 more ft-lbs at 4400. I wanted max HP and regularly rev it past 7k rpm. I too, know nothing about delkevic but it does look nice.

and your most likely getting better mpg with the Vikings. I picked up 2-3 mpg with them. I stated before due to all my research on exhaust systems and dyno time that the OEM headers are slightly under sized due to EPA regs and/or Honda wanted to keep the HP/ftlb numbers down. There is a balance to be had for header ID size. Plenty of studies out there showing esp by David Vizard that smaller ID pipes for street is not always the best esp for MPG and max HP and esp for an engine with the red-line the valkyrie has. I tried to explained this to the muffler replacement guy in another thread, but he just keeps posting what was known 20+ yrs ago. He is now on my ignore list, the first one ever to make it. The Delkevic's are a slightly larger ID and will provide an mpg boost and some HP and torque.

[rocketray]

Meathead there was an  aftermarket ignition box -DYNA 3,000? that quite a few of us have--ask Willow-he has one--that had several different ignition curves and raised the rev limiter--to 7,200 rpm--I saw some 8,200 on a missed shift and thank my lucky star it didn't blow up--it was a must have as I recall for  a blower bike--I called them many years ago for some reason--apparently some of the early ones quit working/had problems and they fixed that but they seemed unhappy  generally with some heavy whiners from the Valkyrie crowd and stopped making them or servicing them. I thoroughly enjoy showing up at Strokers here in Dallas--Rick Fairless's place--and whacking the open Viking header to 7,200 RPM as I enter the open patio area--the Hardly crowds heads whip around so hard and fast I have to pass out muscle relaxants and ice packs   but it is an earplug bike...I at one point had a 6 degree trigger wheel on it at the same time but at much over 5kRPM it was getting way over advanced timing and I was lucky not to burn my pistons up

[MarkT]

The Delkevic's will reduce lower RPM torque and throttle response with minimal scavenging or reversion.  May improve high speed HP if you have Attic Rat mods.  Over 1500 happy owners of my exhaust mods since 1999. They fact they benefit from tech known 20 years ago strengthens their physics; rather than reduces it due to recent ideas that vaquero implies now discredit the proven tech.  I have them on my blown Valk w/o Attic Rat's mods and it makes a bit over 150hp on the dyno.  W/O losing low-end torque.  Granted these pipes are more custom than most I build but they still have the same headers. This bike also consistently delivers around 37mpg rather than the 34 both of my daily riders do.  All with my pipes. Not sure what vaquero's problem or agenda is.  Purports to have better research on Valkyrie headers than the Honda engineering team does.  Yeah right.  I couldn't care less if he "ignores" me. Pretty sure he's not supporting this club as I am.  Knew he couldn't stop beating his BS drum.  BTW vaquero - I keep a list too.  Of known PITA's who are disqualified to be customers.  Of everything I make.

BTW - I never said my pipes are the best answer for everyone.  Mine retain the clean look of chrome that doesn't color with the Honda double wall headers, while I have added power and torque by recovering the OEM's energy wasted pushing through the high back pressure OEM mufflers, and added scavenging.  With my addition of sound adjustment options and custom looks with 4 or 5 inch stacks, the Organ Pipe custom look, length changes and opening style choices - as well as a crossover option.  No they aren't as lightweight as say Super Trapps.  But mine are way more versatile.

[Bagger John - #3785]

...I don't understand why some members of this forum cannot have a civil discussion..they are right and that's the end...

That dynamic is by no means isolated to this board, nor is it isolated to this time frame.

A quick f'rinstance: Any VRCCers who are also COGgers are probably aware of the ongoing pi$$ing match between their (now ex) long-time Tech Editor and his chief antagonist.

I bypassed this board's bad-word filter with a word modification which IMHO is at the root of the COG debacle, but it's up for the viewer to really decide.

Now pass the pipes - peace, or otherwise. 

[Bigwolf]

Well, based on my dyno sheets.... you're both right... I have attic rat mods to my bike so, that changes it a bit. I dyno'ed with mark-t exhaust with crossover (factory headers) and then again with Vikings (larger headers) no jetting change. The mark t exhaust is the slight torque winner  until about 3800 rpm. Then the Vikings take over with 9 more horse power at difference at 6500 and 6 more ft-lbs at 4400. I wanted max HP and regularly rev it past 7k rpm. I too, know nothing about delkevic but it does look nice.

Dago Mooserider, That is good information to know.  I am not surprised at those numbers with the Attic Rat mods and the larger primary exhaust.  Am I correct in thinking that the Viking exhaust has equal length primary pipes?  It seems to me that I was looking at a set recently and the owner told me they were equal length.  If that is true, then they would give a much stronger response in a much narrower RPM range.  The OEM primary pipes are different lengths because that brings power to the max at different rpms for different cylinders.  It is this very design in the OEM exhaust that creates the very broad power band the stock Valkyrie has and allows roll on of throttle from 1500 rpm to 7000 rpm.  If you run at or above 6000 rpm most of the time, you may not have noticed a sudden surge of power at maybe 4400 rpm.  Have you noticed a surge in power at a certain rpm?  I would like to know.

Bigwolf

[The emperor has no clothes]

...I don't understand why some members of this forum cannot have a civil discussion..they are right and that's the end...

That dynamic is by no means isolated to this board, nor is it isolated to this time frame.

A quick f'rinstance: Any VRCCers who are also COGgers are probably aware of the ongoing pi$$ing match between their (now ex) long-time Tech Editor and his chief antagonist.

I bypassed this board's bad-word filter with a word modification which IMHO is at the root of the COG debacle, but it's up for the viewer to really decide.

Now pass the pipes - peace, or otherwise. 

Forgive my ignorance. But what are COGgers ?

[98valk]

...I don't understand why some members of this forum cannot have a civil discussion..they are right and that's the end...

That dynamic is by no means isolated to this board, nor is it isolated to this time frame.

A quick f'rinstance: Any VRCCers who are also COGgers are probably aware of the ongoing pi$$ing match between their (now ex) long-time Tech Editor and his chief antagonist.

I bypassed this board's bad-word filter with a word modification which IMHO is at the root of the COG debacle, but it's up for the viewer to really decide.

Now pass the pipes - peace, or otherwise. 

Forgive my ignorance. But what are COGgers ?

Concours Owners Group (COG).

[98valk]

Well, based on my dyno sheets.... you're both right... I have attic rat mods to my bike so, that changes it a bit. I dyno'ed with mark-t exhaust with crossover (factory headers) and then again with Vikings (larger headers) no jetting change. The mark t exhaust is the slight torque winner  until about 3800 rpm. Then the Vikings take over with 9 more horse power at difference at 6500 and 6 more ft-lbs at 4400. I wanted max HP and regularly rev it past 7k rpm. I too, know nothing about delkevic but it does look nice.

Dago Mooserider, That is good information to know.  I am not surprised at those numbers with the Attic Rat mods and the larger primary exhaust.  Am I correct in thinking that the Viking exhaust has equal length primary pipes?  It seems to me that I was looking at a set recently and the owner told me they were equal length.  If that is true, then they would give a much stronger response in a much narrower RPM range.  The OEM primary pipes are different lengths because that brings power to the max at different rpms for different cylinders.  It is this very design in the OEM exhaust that creates the very broad power band the stock Valkyrie has and allows roll on of throttle from 1500 rpm to 7000 rpm.  If you run at or above 6000 rpm most of the time, you may not have noticed a sudden surge of power at maybe 4400 rpm.  Have you noticed a surge in power at a certain rpm?  I would like to know.

Bigwolf

the Vikings are equal length. buy them if avail. they also use a pre-chamber in the exhaust muffler when the baffle is installed per David Vizard testing.
able to roll on the throttle due to the very basic ICM that honda used, so there is zero pinging. exhaust didn't have much to do with that.
per many articles the smaller ID pipes also cause a dilution of the incoming air charge thereby causing an EGR effect for emissions. The non-49 state cams also cause internal EGR, reducing ft/lbs and mpg.  Just about all modern vehicles now use internal EGR but it works when sophisticated computerized ICMs and variable cam timing are employed.
great exhaust design info. Enjoy.
http://www.formula1-dictionary.net/exhaust_road_perf.html

[Houdini]

Enjoy.
http://www.formula1-dictionary.net/exhaust_road_perf.html

Good read, it verified that the physics of exhaust hasn't changed in 20 years.

Infomration from the link

"No exhaust system is ideal for all applications. At different RPMs, different sized exhaust tubes are more desirable than others. For instance, at low RPMs you would want a small diameter exhaust pipe to give some backpressure and increase low rpm torque, while at high RPMs you would want a large diameter exhaust pipe to be able to let out the exhaust gases quickly and easily, but keeping very little amount of backpressure. But it is not a direct RPM/exhaust size relationship that is only important, but it varies with manifold pressure as well. Both works together to produce exhaust pressure.

Depending on their design and purpose, all exhaust systems compromise something to achieve something else. Before manufacturing an exhaust or modifying existing stock to increase performance, it is critical to determine what kind of performance you want.

•  Do you want the best possible low-end and mid-range power or maximum top-end power?
•  You have to investigate the relationship between torque and horsepower

Without careful thought about these variables, an exhaust system can produce very disappointing results. On the other hand, a properly designed and tuned exhaust system that is well-matched to the engine can provide outstanding power gains.
A very common mistake made by some performance people is the selection of an exhaust system with pipes that are too large in diameter for their engine's state of tune. Bigger is not necessarily better and is often worse.

One of the biggest issues with exhaust systems is the relationship between gas flow volume and gas flow velocity (which also applies to the intake track). An engine needs the highest flow velocity possible for quick throttle response and torque throughout the low-to-mid range portion of the power band. The same engine also needs the highest flow volume possible throughout the mid-to-high range portion of the power band for maximum performance. This is where a fundamental conflict arises. For "X" amount of exhaust pressure at an exhaust valve, a smaller diameter exhaust pipe will provide higher flow velocity than a larger diameter pipe. Unfortunately, the laws of physics will not allow that same small diameter pipe to flow sufficient volume to realize maximum possible power at higher RPM. If we install a larger diameter pipe, we will have enough flow volume for maximum power at mid-to-high RPM, but the flow velocity will decrease and low-to-mid range throttle response and torque will suffer. This is the primary paradox of exhaust flow dynamics and the solution is usually a design compromise that produces an acceptable amount of throttle response, torque and horsepower across the entire power band."

It appears that physics and MarkT are correct.   

[98valk]

Enjoy.
http://www.formula1-dictionary.net/exhaust_road_perf.html

Good read, it verified that the physics of exhaust hasn't changed in 20 years.

Infomration from the link

"No exhaust system is ideal for all applications. At different RPMs, different sized exhaust tubes are more desirable than others. For instance, at low RPMs you would want a small diameter exhaust pipe to give some backpressure and increase low rpm torque, while at high RPMs you would want a large diameter exhaust pipe to be able to let out the exhaust gases quickly and easily, but keeping very little amount of backpressure. But it is not a direct RPM/exhaust size relationship that is only important, but it varies with manifold pressure as well. Both works together to produce exhaust pressure.

Depending on their design and purpose, all exhaust systems compromise something to achieve something else. Before manufacturing an exhaust or modifying existing stock to increase performance, it is critical to determine what kind of performance you want.

•  Do you want the best possible low-end and mid-range power or maximum top-end power?
•  You have to investigate the relationship between torque and horsepower

Without careful thought about these variables, an exhaust system can produce very disappointing results. On the other hand, a properly designed and tuned exhaust system that is well-matched to the engine can provide outstanding power gains.
A very common mistake made by some performance people is the selection of an exhaust system with pipes that are too large in diameter for their engine's state of tune. Bigger is not necessarily better and is often worse.

One of the biggest issues with exhaust systems is the relationship between gas flow volume and gas flow velocity (which also applies to the intake track). An engine needs the highest flow velocity possible for quick throttle response and torque throughout the low-to-mid range portion of the power band. The same engine also needs the highest flow volume possible throughout the mid-to-high range portion of the power band for maximum performance. This is where a fundamental conflict arises. For "X" amount of exhaust pressure at an exhaust valve, a smaller diameter exhaust pipe will provide higher flow velocity than a larger diameter pipe. Unfortunately, the laws of physics will not allow that same small diameter pipe to flow sufficient volume to realize maximum possible power at higher RPM. If we install a larger diameter pipe, we will have enough flow volume for maximum power at mid-to-high RPM, but the flow velocity will decrease and low-to-mid range throttle response and torque will suffer. This is the primary paradox of exhaust flow dynamics and the solution is usually a design compromise that produces an acceptable amount of throttle response, torque and horsepower across the entire power band."

It appears that physics and MarkT are correct.   

all I have ever said is that the OEM exhaust is on the small side and is restricting the engine. make it even smaller and the torque will go up some more in the lower rpms.  The Delkevic and Viking are slightly larger helping the full rpm range of the engine for more power and mpg to be utilized. tried to explain this to the muffler replacement guy in another thread but he just shut his mind to a conversation about it, he sees it as hurting his business. so he is neither correct or non-correct.
 I said there is a balance to achieve which the viking and delk achive IMO, he would have none of it.  Hey yrs ago I even tried to tell people that a crossover was actually not good for a six cylinder engine except for noise reduction. and if it cannot be correctly installed the correct distance from engine which is most likely the case with a motorcycle from what I have read, there actually would be a reduction in torque. the muffler guy poo-poo'd me away then (he was making money installing them), also as others did. always works on a V-8, not always for six cylinder engines which are even firing engines.
one such write up on cross overs. there are many. Enjoy!
https://mustangforums.com/forum/2005-2014-mustangs/96138-cross-over-exhaust-pipe-explained.html

[MarkT]

Yours is a completely wrong mischaracterization of my position which is still clearly posted unedited for those without your agenda, to read. THIS is what I said: http://www.valkyrieforum.com/bbs/index.php/topic,98222.msg976485.html#msg976485

 You sir, are a LIAR.  I agree with all the other posts - by others - in this thread while you are largely full of beans.  To be nice. Did you get your political spin training at the DNC?  They are also liars and spin doctors.  I agree with these 2 sentences below - with caveats - the restriction being the OEM pipes were not designed for racing so they can be restrictive at high rpms, like when racing, particularly if the engine has other breathing improvements like head work.  However the Valkyrie is not designed for racing, it's a street/road bike.  To race, get a bike designed for it.  Like liter sport bikes, or the Hiyabusa or ZX-14.  Other caveat - large diameter headers only help at the high rpm ranges.  Don't help at lower rpms, like riding on the street.  Actually HURT torque and response then.  I haven't seen anything other than your claims about such pipes helping mileage.  And YOU - with your agenda - I don't believe w/o other proof.

"...the OEM exhaust is on the small side and is restricting the engine. make it even smaller and the torque will go up some more in the lower rpms.  The Delkevic and Viking are slightly larger helping the full rpm range of the engine for more power and mpg to be utilized."

I already said what Houdini reprinted above, and apparently came from the site YOU linked.

The rest you wrote is CRAP.  And I see no bona fides you can speak from.  Other than your boasting.  Where is your flow dynamics degree from?  Oh yeah.  Don't have one.  Or much experience.  Do you have ANY education?  I do.  

Like I said above.  I'm not promoting my custom exhausts anymore, other than the banner ad.  I'm OK with filling orders as they come in from my reputation.  I'm not retired yet but I'm now taking it easy.  OTOH - YOU are doing a disservice to new riders who know less about their bikes and exhausts if you keep pushing your anti-MarkT agenda.  Like I said - I don't know where this is coming from.  I've spent much of the last 18 years helping people on these boards by sharing what I learned mostly the hard way. I was here on the first day, when Gale Scalzi "Oz" asked me to co-edit this site with him. I declined as I was so busy with pipe orders with a 3 month backlog - and I was already Western VP and co-founder of the Valkyrie Owners Assoc.  He asked and Lamont Bryden "Lamonster" accepted the job instead.  I post all the time here with help and advice when I think I can add to the discussion, that pays me not a penny.  And I have always been truthful about my custom work - advising others sometimes to get another exhaust after I know what they are looking for and mine isn't the best for their needs.  eg. they want a lightweight exhaust that still has performance.  That would be Super Trapps.  But here you paint me as a rogue who will say anything to get business.  My customers know better.

Are you jealous?  Do you want to be the Wal-mart of Valkyrie knowledge?  Discrediting others does not buoy you up.

[dago mooserider]

Well, based on my dyno sheets.... you're both right... I have attic rat mods to my bike so, that changes it a bit. I dyno'ed with mark-t exhaust with crossover (factory headers) and then again with Vikings (larger headers) no jetting change. The mark t exhaust is the slight torque winner  until about 3800 rpm. Then the Vikings take over with 9 more horse power at difference at 6500 and 6 more ft-lbs at 4400. I wanted max HP and regularly rev it past 7k rpm. I too, know nothing about delkevic but it does look nice.

Dago Mooserider, That is good information to know.  I am not surprised at those numbers with the Attic Rat mods and the larger primary exhaust.  Am I correct in thinking that the Viking exhaust has equal length primary pipes?  It seems to me that I was looking at a set recently and the owner told me they were equal length.  If that is true, then they would give a much stronger response in a much narrower RPM range.  The OEM primary pipes are different lengths because that brings power to the max at different rpms for different cylinders.  It is this very design in the OEM exhaust that creates the very broad power band the stock Valkyrie has and allows roll on of throttle from 1500 rpm to 7000 rpm.  If you run at or above 6000 rpm most of the time, you may not have noticed a sudden surge of power at maybe 4400 rpm.  Have you noticed a surge in power at a certain rpm?  I would like to know.

Bigwolf



Well, I guess a little bit.  There is a point where the bike feels like the horsepower is taking over instead of the torque. Perhaps is is slightly less smooth than stock but only at wot. I do have the dyna ignition set at 7500 limiter. It's a blast to ride. 120 horsepower and 40 mpgs freeway. My take on the header thing is simply that Honda cares about durability first, performance second. Hence the double wall and chrome that lasts. I was very happy with my mark t exhaust, liked that I could have 3 levels of sound. But I knew after the Attic rat mods, those factory headers were choking it a bit.

[DarkSideR]

Now that the pissing contest is over...

I am selling my Super Trapp Exhaust system if you are interested in a quality exhaust that is tunable, adds HP, and sheds 30lbs.

Email me ValkyrieJosh@gmail.com if you are interested in buying.

DarkSideR 

Oh and they sound like this! (https://www.youtube.com/watch?v=eczVgF_C6iE)

[Bigwolf]

Well, based on my dyno sheets.... you're both right... I have attic rat mods to my bike so, that changes it a bit. I dyno'ed with mark-t exhaust with crossover (factory headers) and then again with Vikings (larger headers) no jetting change. The mark t exhaust is the slight torque winner  until about 3800 rpm. Then the Vikings take over with 9 more horse power at difference at 6500 and 6 more ft-lbs at 4400. I wanted max HP and regularly rev it past 7k rpm. I too, know nothing about delkevic but it does look nice.

Dago Mooserider, That is good information to know.  I am not surprised at those numbers with the Attic Rat mods and the larger primary exhaust.  Am I correct in thinking that the Viking exhaust has equal length primary pipes?  It seems to me that I was looking at a set recently and the owner told me they were equal length.  If that is true, then they would give a much stronger response in a much narrower RPM range.  The OEM primary pipes are different lengths because that brings power to the max at different rpms for different cylinders.  It is this very design in the OEM exhaust that creates the very broad power band the stock Valkyrie has and allows roll on of throttle from 1500 rpm to 7000 rpm.  If you run at or above 6000 rpm most of the time, you may not have noticed a sudden surge of power at maybe 4400 rpm.  Have you noticed a surge in power at a certain rpm?  I would like to know.

Bigwolf



Well, I guess a little bit.  There is a point where the bike feels like the horsepower is taking over instead of the torque. Perhaps is is slightly less smooth than stock but only at wot. I do have the dyna ignition set at 7500 limiter. It's a blast to ride. 120 horsepower and 40 mpgs freeway. My take on the header thing is simply that Honda cares about durability first, performance second. Hence the double wall and chrome that lasts. I was very happy with my mark t exhaust, liked that I could have 3 levels of sound. But I knew after the Attic rat mods, those factory headers were choking it a bit.

Thank you for answering my question.  I don’t think that surge is a bad thing.  It just indicates the point at which the engine is starting to breath well.  I also believe that the Attic Rat mods can benefit from larger than stock exhaust primary pipes.  Good on ya for getting your Valk set up the way you have it.  I am sure it still has plenty of power on the low end and much improved power top end.  Your Dyno numbers  show that too.

Thanks again,
Bigwolf

[98valk]

Now that the pissing contest is over...

I am selling my Super Trapp Exhaust system if you are interested in a quality exhaust that is tunable, adds HP, and sheds 30lbs.

Email me ValkyrieJosh@gmail.com if you are interested in buying.

DarkSideR 

Oh and they sound like this! (https://www.youtube.com/watch?v=eczVgF_C6iE)

super trapp dyno run
http://www.rattlebars.com/mtz/dyno1.html

[powerslave]

  So no one here has the Delkevic system? I'm not worried about max hp ect. I like the 6 into 2 look and the fact they are made of stainless. For now, I'm just going to try getting it to run the best it can with the 6 into 6's.

[98valk]

  So no one here has the Delkevic system? I'm not worried about max hp ect. I like the 6 into 2 look and the fact they are made of stainless. For now, I'm just going to try getting it to run the best it can with the 6 into 6's.

http://www.valkyrieforum.com/bbs/index.php/topic,24312.0.html

see my post of FactoryPro  dyno testing/jetting for cobra's

[petepinto]

https://www.youtube.com/watch?v=HAvWIcr-TIU

I have them. My first impression was that they were a bit too loud at high rpm's. Think I'll "upgrade" the silencers myself. Awesome looks.

[Disco]

I have them for my '78 CB550K.  Look great, sound great, fit great, and very nicely made.