motor and tranny mounts are all new and so are the rear control arms.

 

this is one of those things where i'd have to be there to really figure out, but it shouldn't be too hard.
2.5" pipes should clear everything all the way back. somewhere along the line, something is twisted at an angle, or something like that.

 

I think I stopped the banging around- I just took it for a ride and didnt notice that problem anymore.
Last night it was banging even while idling.

Ive got a whole other noise that isnt the exhaust now in the rear of the car though.

 

I had the exact same problem. My temporary solution was to just run dumps until I found a way to fix it, but I like the dumps and am keeping it like that. Although I do miss the look of the tailpipes.

 

my Flowmaster catback fit awesome, way better than the Bassani does thats for sure. had zero problems with the Flowmasters for like 3 years.