just got my new exhaust system from Burnum Pro. I also bought a carburetor from Burnum. It was definitely worth the wait that guy definitely knows what he is doing after reading several posts and how so many people were happy with their carburetor from Burnum Pro I decided that would be the better carburetor for me. And I understand completely that the FCR does perform better. I do have one on my 2006 crf450r and it runs great But my XR650r will mainly be on the street. I also put the PIAA headlights and Ricky stator 200W. it runs awesome I could not be happier it finally runs like it should. If you want an exhaust that it will make women and children run and put a permagrin on most men. Then the Burnum Pro is definitely an exhaust system you should check out. The more equal length header pipes is what sold me on his exhaust. I'm not sure if that helps performance on a single cylinder motorcycle but it looks great and it definitely can't hurt.