Aside from some pretty fancy work, the Valkyrie is quick as you need, if you get a good tune, air cleaner, carbs in good clean order, carbs properly synched, valves adjusted, damper rubbers good, all vacuum leaks resolved (with or without a desmog of much of it), drool tube drained, proper rear end lube and assembly, clutch fluid clean. The stock pipes breath very well.
The Honda-engineered stock pipes can be improved, however. They have the best streetable torque with their velocity but then they are required to restrict the sound volume by the EPA. As a result, the true muffler reduces power by the friction of all the extra backpressure. Get rid of that, and recover the power wasted. That is, replace it with a Cherry Bomb or the like. Put in a header collector and gain scavenging. Add a crossover to improve torque more. Do this to the OEM exhaust and keep the double wall headers that don't color if you don't overheat them. That is, don't run the engine too rich or lean; don't run the bike in the garage for long, unless you set up a fan to cool the pipes.
You may know I provide these upgrades since '99 - along with other options you can choose, like silencers, Trombones, Organ Pipes, Crossover, 4 or 5 inch stacks, so you can set it up to change sound easily, go louder or quieter with noticeable more power and w/o rejetting. Cheaper if you provide the cores to build on. I also do core exchanges when they are available. The exhaust banner above, appears frequently, will take you to my exhaust site.
