The very first manufacturer's web site that I visited 10 seconds ago was D&D. I will be going to the D&D Fatcat for Touring models. Here's what the D&D web site says:

"Performance increases are about up to 15% with the proper tune on the bike."

That's stock motor.

http://www.danddexhaust.com/content/...21-full-system

 

Thanks, I will search more for what I am looking for...but even in those words....UP TO 15%...15% is a perfect world I would venture....

 

Try this hot rod tune and a couple auto tunes!