I bought this pipe for my 07' CRF450R in anticipation that it would smooth the power like the Dr D of past. WOW was I wrong, hold on to your panties, mid to top was out of this world, not what I was looking for but not a negative. I give this pipe bad marks in the Durability category, the rear mount broke, which is common but I never let the bolts get loose and there was less than 15 hours on this pipe. That being said, I am not much past Junior local level and nowhere near hard core. If just the mount broke I would be okay with it but the entire core was ruined, I'll replace it with a disposable FMF.