Akrapovic full exhaust popping/backfiring?

When I downshift in to 1st gear sometimes (2nd and 3rd) when preparing to stop my exhaust makes a popping/cackling sound. I think it sounds pretty sweet, but is this causing any damage to the engine? Running lean, etc? Or....? Does anybody elses exhaust do this? I figured that since the full exhaust removes the cats and all that that this is probably pretty normal and common? :dontknow:

Thanks!