I would go with the exhaust system as well, those hangers could be worn out.

 

Thanks for the replies.

I'll double check them. The hangers are new but clearly shoddy (thanks, Meineke!) - the entire cat-back job they did was incredibly sloppy. They were too lazy to make a new S-pipe so they reused mine and as a result there's about 8 welds behind the cat where tiny sections of pipe were put together to make my old stuff fit with some new sections.