I have the Pro Circuit pipe for my 2001 KDX200 and man was it the best thing I ever done to it! Don't buy an FMF because the fit is terrible! I'm not saying this just because I'm a Pro Circuit fan but seriously, FMF is terrible. The PC pipe makes the KDX rev to the moon (I mean she just doesn't want to stop pulling), it is terrific. It took away a little bottom end for trade with more top end power. But, hey if you want that overrev power (like me) then this pipe is the ticket. I don't know if you've ever noticed but the stock pipe is made so you can ride in 6th gear full throttle and hold it. The PC pipe does not allow you to hold it because if you hold it too long then you're going to blow your motor. Also, I bought the 304 Factory Sound silencer to go along with it. It is not a spark arrester but sounds really cool! It is up to you if you want it quiet or not. But, definetly get the pipe, it is worth all $150!!!!!!!!