what jetting, it depends where you are B) about 3000 ft and below you should be able to go up to about a 185 main. Take the baffle out of the muffler, and get another "high flow" air filter. and you will be twice as fast. You can enhance it even more with a HRC end cap, I can sell you my old one for 20 dollars plus shipping if you want it. It makes it sound much better.