Will a k and n jet kit and filter together do much performance without a pipe? Also, which size jet would be good for a stock 300ex except with a k and n air filter and should the needle be moved at all?
Thanks in advance

 

Come on, someone here must know this one.

 

It will give u a little more power. Just buy the K&N power kit and there's jetting instructions in there

 

Man, good timing. I JUST did these mods today, about 2 hours ago. It really did make a difference, albeit a small one. I did a Dynojet stage 1 jet kit, a k&n filter element and an outerwear filter cover. No holes in the airbox lid and its left on, due to dust and water. Anyways, the quad is stock otherwise. I have a 2003 400EX, but the 300 should respond similarly. Results, pulls better in the lower end. I didn't get to top it out yet, but I'll let you know after this weekend. It actually seemed to make the quad smoother running and quieter at idle and just off idle. I have the 142 (dynojet number) main jet, dynojet needle at 3rd groove, and mix screw out 3 1/2 turns. Runs nice. I got all of my stuff from rockymountainatv.com for just under $100. Good luck if you decide to go with it. Its an easy job as long as you have some mechanical skill (if you can change oil, you can do this). Have fun and stay safe.

 

If u want another little boost try a tooth smaller on the front sprocket

 

Thanks you guys