I've done the free mods, and jetting. I just installed a Muzzy's system, and the popping is much louder, more pronounced and much more annoying than it was before. I realize that this popping was there before, only the exhaust system makes it more obvious now. I heard that the popping is due mostly to the AIS system. To test this, I ran the bike in nuetral while squeezing the larger rubber hose of the AIS shut with needle nose plyers. NO POPPING WHATSOVER!!! I released the plyers, allowing the AIS to resume running, and the popping came back full force. I am astonished that I literally could not induce even the slightest pop with the hose pinched even while revving like crazy. Perhaps many of us don't need to worry about our pilot jets or fuels screws as the incessant back firing could literally be cured with nothing more than a zip- tie. I have already ordered the Lowedog kit (thanks Lowedog), but I am beginning to think that simple corking or plugging the main hose might be the answer, as it is a less permanant solution, and keeps the bike's original equipment intact. Has anyone gone this route? Could it have any negative consequences?