Hey guys! I just got a new FMF powercore 4 for my 09 WR, I got to tell you what a difference that pipe makes! I can really feel the power gains thru out! My question is, I got the GYTR AIS removal kit, I think it comes with a 50 pilot jet, I have read on here people are going with something lie a 45 or 48, I got all three, which one should I use! Oh yea, the pipe is not too loud, Its louder than stock, but not to crazy loud! I like it!!!!!