Popping on the over-run is a contentious issue; some will say it is cos there is an air leak in the exhaust, some cos the bike is running lean, some cos it's running rich.
I subscribe to the third (with air being sucked back up the exhaust during the scavenge period when the throttle is closed) and got rid of all my popping and banging by winding the fuelling down to a trickle (10) at the TPS for closed throttle.
Daywalker has done some experiments with his Remus with baffles in and out. IIRC, it pops more with the baffles out (less restriction to suck air back through the exhaust).
On the over-run, the ECM is in Open Loop, so the fuel map is affected by the AFV. Higher AFV, more popping and banging.
Interesting that ph's bike pops and bangs more when it is running shite. I wonder if your Larry-the-Lambda sensor is poorly, perhaps contaminated