I have a 89 kdx 200 that I completely rebuilt last year and I even did daves (create your own secert weapon) by hollowing out your oem pipe. I works great but I have had alot of trouble getting the jetting correct. Even the dealer couldnot get it right. (always to rich) and trust me the dealer doesn't look at it for under a $100.00 every visit. I have a fmf gold series pipe with a turbine core arrestor that I going to try this year but I have no idea what the jetting should be for it. I live in lower Ontario Canada so If that helps with sealevel and temp that I ride in.