I have the same issues with mine. It farts on deceleration. Remapping my fuel map to zero on deceleration was a help however the instant fuel is reapplied just above idle it pops. Drives me nuts.
The exhaust is made up of headers, resonators, and fat cans. It’s an air tight 2 ½ " system.
The racing V12s and turbo Porches at the track do the same thing.
However Ed is right, the ladies don’t like it.
I now suspect it is ignition timing related. Fuel not sparked in the cylinder making it’s way into the pipes?