My brother just installed a Power-Up kit and a Big Gun Race exhaust system. He rejetted to a 178 main provided by baja designs. When he restarted the bike it was backfiring just above idle and on deceleration. It also has a dead spot at 1/4 throttle where it will buck/jump/miss, and then it will hesitate reving to WOT from that point. He changed the pilot jet from a 65s to a 68s and he said it seemed to help. He also turned the idle air screw out to 2 3/4 turns and said that it was a little better but any further and it made it worse. I think he needs to go richer on the pilot. What do you guys think?