i have a raptor 350 and put a hmf slip on pipe on my bike and i don't know if i have to jet it or not and i need help so it would be help ful

 

You will have get it jetted otherwise you will be running to lean and you wont notice any real performance increase till you do that. It would be a good idea to put on a better air filter or remove your lid to make breathe better if you havent already. I had mine jetted for me. when your re-jetting a carb sometimes you have to try a couple of differents jet combo's to find the right one.

 

Buy the pipe! Then get a dynojet jet kit from ebay. Then get a K&N filter. This combo REALLY wakes up the raptor.You wont regret it.