Ok I got my 06 FLHRI Road King. It has a 95" kit in it from the dealer and had cycle shack slip on mufflers. It was back Firing and I took it to my mechanic. I change the pipe to Vance and Hines and put a TTS Tuner in it. I had him change all the fluids and check out the bike. When he test road it he said it still had a little grumble in it but didnt back fire. I rode it home and after a few miles it startedto back fire, so my mechanic is going to adjust the tuner and see if that helps. a few people told me to get true dual exhaust and that should help. Also my mechanic said they may not have changed the cams when they did the 95" kit and they may be to small. Since I bought the bike used maybe the gas went bad or they used the cheap gas and not 91 octane. Any thoughts on this?