i installed the cherry bomb muffler about 1500 miles ago. The sound is so nice that i put up with a gunshot like backfire/afterfire. it would do it once or twice every ride. i tried blocking the pair valve and adding fuel with a Techlusion fuel nanny with no luck. after a google search i found the problem. i didn't use any gasket material on the muffler joint and i had a air leak. after 100 miles no more backfire. hope this may help someone else. i also drilled and installed two sheet metal screws to make sure the muffler cant blow off.