I have the BG slip on silencer and put in the reccomended jets 150/155 with 25 pilots. It ran like crap, changed to 145/150 25 pilots and it seems better but havent ridden yet. I am still running the stock air filter. Does anyone know if the other jet in the left? carb that looks like a main? should that be changed too? What is its purpose? Kinda wierd seeing 1 main jets in one carb..... In case you havent guessed it's for the RAPTOR. yeah added late, sorry..

??

Buy the Dyno jett kit and be done with it! Skydog[img]i/expressions/face-icon-small-smile.gif[/img]

I have the big gun slip on too and i didnt change any jets and it runs great! try to go back to stock jetting and see what happens if u havent already done so. I am wondering how much the head pipe will help it and if its worth 200 bucks??

a couple of items here: get an aftermarket airfilter and open up your airbox, this will help you get the most from your exhaust. did you adjust the airfuel mix screw? how does the plug look? when you say running like crap: low end? high end?
my shop manual lists the other jet as a starter jet, it is on the left for the starter fuel circuit

just go up one size on the main jets and you should be ok. My friend did this and his runs fine.