my hmf pipe says its for a rubicon and is totally different from my buddies 04 forman, the way it 'rounds the shock... i would definatley do the jet kit, i know u would hate to burn that brand new atv up because it was toooo lean... i did both at the same time so i dunno the difference between 1 or the other. i didnt do the air filter untill later and that made a bigger difference!! just like flowmasters motto..."GOTTA LOVE THAT SOUND" and of corse spin the **** out of all 4 tires well at least 3