i have a new raptor 350 and im considering getting a k&n airfilter and when i get this would i have to buy a new air box and would i have to rejet for the k&n? and i also want to get a HMF exhaust pipe(slip on) will i have to rejet for this?

 

well if ur gettin a K&N and then a lil later gettin the pipe dont jet untill u get the pipe so u dont have to do it over again it should be fine till u get ur pipe

 

Either wait till you can buy both at the same time or you'll have to jet twice. I highly recommend jetting if your putting on a new filter. The only real way to know if you will have to rejet is to put it in and ride it though. Most bikes come stock a little lean so putting in a new filter will just lean it out more which isn't good on the engine, better safe than sorry.

You know you'll have to jet up if it's harder to start, hesitates/pops on full throttle, idles slow/rough, or gets hot fast.