ZL1 factory NPP exhaust packing blowout after mods??
 

So I was washing my car and looked into the tailpipe and thought there was a live animal in there!! Turns out the packing material in the NPP stock muffler is coming out. So I do have Forza controller and do keep it closed quite a bit. Defect or not designed to host that much power at WOT??

Hey stupid why don't you search first:
http://www.camaro5.com/forums/showthread.php?t=264328

Sorry didn't see this before

^^^ Lol. Mine didn't do it until I was heavily modded. It sometimes has the NPP rattle on cold start up if the flaps are closed (I have an ADM exhaust controller).

Doesn't matter if you are modded or not. Mine went at 3400 miles with no MODS but CAI.

Very common for GM exhausts. Its perfectly fine; You won't have problems, as a matter of fact the exhaust may get louder.