I just purchased my 1st quad, a 2003 Raptor. I'm a 34 year old portly fellow (270lbs.) who needs a little edge to keep things even with my skinny riding buddy. I'm thinking a pro design k&n setup (lid removed or butchered up) and jetting with the spark arrestor removed will give me enough to keep up with the stockers. Will the extra air and fuel be handled by the stock exhaust or is aftermarket exhaust a must for proper balance? I'm not really wanting to go ape buying aftermarket crap for this thing, I just need a little more horsepower for now. Frankly, I'm tired of searching through posts for ideas so I decided to just join in and ask.

 

Welcome aboard! Im a fatty too, I got a gytr slip on (dont recommend since its falling apart) and cut the back end of my lid off behind the first set of clips then jetted up to 160/165. Very nice improvement on top end (where us big guys want it) Luckily I havent had any of the turbulence issues associated with the cv carbs that my skinny friends have so I fair well against them.

I turned my air screws out another 1/4 turn too. I kept the original air filter, I have about 4 that I swap out after every ride then clean and re-oil.

I put a dynojet kit in my skinny friends raptor and we were really dissapointed, neither of us could get his raptors front end off the ground even in 2nd on pavement, like he lost power. Then we jumped on mine and could get third gear up easy as pie.