I just bought the quad got a killer deal but have some issues. The quad has an after market pipe that is loud as all get out( no packing) I’ve ordered packing but it’s loosing some power at full throttle and backfires when you let up. Could this be jetting? Valves need adjusted? Carb needs tuned? I have no clue really. It has not been modified other than this loud a$$ pipe. Any help would be great.