Today I finally went riding with my HMF pipe, I took out the quiet core, and let i all hang out. I have one question though. I think I was hitting the rev limiter, but I'm not sure. I started the bike and hit the gas for a second and let it rev up a bit, and i heard a wierd sound at the very top end, at first i thought it was a jetting probelm it kind of sound like it was breaking up, then i noticed it more and more when i was in 1st, 2nd and 3rd and i was trying to push the revs. I was just about to rejet it, but my buddy told me it might be my rev limter, I have read many times that when guys get a new pipe, they hit the rev limiter much faster. I'm going to go back to a 14t front sprocket if it is the rev limiter, i definately think i can now, with all the added torque!!!