The April issue of American Iron shows an install of this kit on a stock engine. They do some dyno runs and show the power increase with the air cleaner and then again with the mufflers never taking the bike off the dyno. I don't remember the numbers but there was a power increase with the A/C but almost no gain when adding the mufflers which to me is fine. The thing that struck me was they did nothing to the fuel mixture stating that the system would adjust itself after about 15 minutes of run time. I was under the impression that the stock HD system didn't do much adjusting. If the system can adjust itself, why does HD do the Stage 1 download? If the bike were running lean, would it show up on the dyno? I believe this was done at a HD dealer.