Bike backfires into a quite muffler = you CAN'T hear it
Bike backfires into a loud muffler = you CAN hear it

Bike most likely has always backfired a little as is very common with these engines. No biggie.

 

When it backfires it sounds like your next to the muzzle of a gun going off. Its far from little

 

Usually not a bad idea to put a light, uniform film of Permatex Ultra Copper on the exhuast joint. This will seal up the joint and also prevent the mufflers from seizing to the headpipes making future removal easier.

 

If moisture can make it out then air can make it in. I just put Rinehart slip ons on my '09 and it called for 40-60 ft/lbs of torque for each clamp. I did right at 60 with no leaks. If you hold your hand near the connection with it running do you feel any air, blow some cigarette smoke at it. I've put 400 miles on mine since installing last Wednesday and I can't get mine to backfire at all. I don't have an aftermarket a/c or tuner though.

 

What kind of gun?

 

THE permatex cu gasket sealant worked for me no more pops-ride safe

 

I hope it's a Kimber 1911, they sound great :-) Seriously, I had the same problem when decelerating. I did as suggested by the PC guys and enrichened the mixture at 0% throttle. No more popping or backfiring.