I have a slip on, open air box and a K&N. I am running a 42 pilot and 160 main. 600 ft. elevation. Just currious what others are jetted at? I also put a diff. needle in it and raised it one knotch from the stock setting. It seemes to run great, but at WOT for a long period of time it starts to break up like its running out of gas and back fires. If I pull the clutch and rev it a few times its back to normal. It pulls like a mad man thru every gear and is the fastest one out of my group I ride w/. All 400 ex's. Any input would be great. When I adjust my valves soon, im going to put a cam in. Any suggestions there? My motor is still stock internals. Ive heard Hotcam stage II.???