look you dont need back pressure. my america will leave a black mark down the street how ever long you want. All i did was install the unifilter, remove the snorkel, install 130 mains, shim the needle .9 mm, turned out the jet screw to 2 1/2 turns out from closed, and remove the silencers.
I installed some 18" turn downs. I beat a 1200 sportster off the line and he could never make the distance back threw all 5. I stayed ahead of him 1/2 a bike length. I know you dont want to hurt your bike but trying to beat out the baffles or punch an over sized hole in them is way out there. I put 22" x 3 1/2" slash cuts on my friends bike $105 for both. at a muffle shop and my 18" turn downs $40. For the price of performance replacements you can go to a custom exhaust shop and have some thing completely unique built.
