Hello, I have a JD jetting kit on my 2004 WR450 currently and the bike runs nicely but i have just got a full FMF factory 4 full exhaust system (inc header) which included the FMF jetting kit. My friend has the exact same bike with the same exhaust and JD jetting kit and his bike runs well so i know its a good combo. Does anybody know much about FMF jetting kits? Are they any good? Which jetting kit would you use, stick with the JD or swap it for the FMF? Cheers Lennie.