I just got the AWE Touring cat back non resonated on mine a couple of weeks a go and absolutely love it! ZL1 is all stock with the exception of the Rotofab CAI.
Zero highway drone in fact can hardly tell the difference! Down shift or floor it and holy hell .... It sounds like a true muscle car now! .... Cold start is pretty loud now but I am blessed with pretty cool neighbors that are also hot rodders so they are cool with it!
I hear what others are saying about systems with Headers and that would probably too much but for now I wanted to increase the sound with a warranty.
https://youtu.be/O_dkCc0dmM4