i just put on new 2.5 inch. exhaust all the way back. and there is a rattle at the bumper "hole" where the tip sticks out. how can i fix this? by the way. all the bolts and hangers are secure and there is nothing loose.
It's probably the hangers, try adjusting those, switch em to a higher or lower ones. If it sounds like metal, then it's probably your heat shields but those are closer to the middle of the car than the rear.
this usually happens on crush bent custom exhausts. since most of them are made in one piece they are not a great fit and tend to rattle. my first exhaust was crush bent and it use to rattle too and shake the muffler.