I've been hearing the bang from time to time, I was thinking it was in the suspension, perhaps the sway bar loading and unloading cause I notice it most when I'm heavy on the gas after changing gears (reverse to forward), with all the noise there does not seem to be a harsh physical jolt that accompanies the noise. The noise does not seem to be muffled like it is coming from inside something. Just some thoughts.
I think the pop is a lean backfire, I notice it mostly when backing down form high RPM with a small amount of throttle applied!