MarkT?
One of the only guys still making cool aftermarket pipes for the old
Valkyrie. He makes them from OEM pipes. He is a vendor for this
club, and his ad "Horseapple Ranch" will be at the top of the page
a lot of the time. He doesn't have a new Valkyrie and probably
doesn't care anything about making pipes for them, but if he
did they would probably be good...
His pipes are supposed to make more HP, and have all kinds of
bling options...
-Mike
To expand on what Mike said, I bought MarkT's Mild2wild system and loved it. He takes your stock system(or he may have cores you can buy) and cuts off the exhaust behind the headers. He then adds a glasspack(18inch is the usual) and then gives options of trombones(pipes that go into the packs and cancel some or all of the glasspacks muffling effects. He also makes a silencer out of your old rear cans that is held in by one screw per side. So the bike can sound anywhere from almost stock to almost straight pipe. It changes over in seconds. You can get them made in a variety of cuts/turndowns and can go with a 4 inch system or even 5 inch stacks. It's all VERY quality work.