New HMF Competition series full exhaust

[Ou812cd1]

Hello all newbie here....

I just bought my son a HMF competition series full exhaust for his 2006 Honda 300EX along with the jet kit for Christmas. My question is the Basic Jet Kits Includes: Individual Keihin Hex Jet: 120, 125, 130 , which needle is going to give him the most power? Also he already has a K & N filter installed. As you all can probably tell this will be my first go around adding an exhaust system and a jet kit to an ATV. Thanks in advance for any help!!

[trx#9]

I wouldn't worry about getting a different needle right now, the stock needle isn't going to hold anything back. Since he has a k&n filter i would start with the larger main jet and let her rip.
Welcome to the forum.....