From what I've understood... The pilot jet only controls the idle mixture. The needle takes care of the mid throttle and the main jets take care of full throttle. Am I right? The only reason I'm asking is I might get a yosh' 4-2-1 system and was wandering if just shimming the needles and increasing my mains is all I would need. I reall don't want to pay $300 for and exhaust when I have to spend another $150 for a jet kit. That's alot of money, for little gain.

 

Give it a try...the spendy part of a jet kit is the dynotime developed needles, kit makers will generaly sell you anything seperate, in the kit... but the needles. I have shimed.. and had good results... but a dyno does illuminate the truth.Worth a cheap try.You'll know pretty quick, how "close" you got. Clean and free, Ripp'n