Oh well better late than never 9 month old thread. I have the stage 1 kit on my '07 Night Rod Special. I installed the TAB chrome slash-cut slip-ons along with a hi-flo air filter and cobra fuel manager. Can't say that I felt an overwhelming difference in power perhaps slightly but it most definitely breaths & sounds much healthier than the stock cans. Enjoyin this stage 1 upgrade fer now. Who knows, maybe consider a stage 2 (cams)upgrade in the near future ...hope this helps!