I have a 97 4Runner and I recently put a new muffler and tailpipe on. I didn't notice it immediately after installation, but now whenever I am driving there is a really bad rattle due to the fact that the tailpipe is hitting the top of the rear axel. I was thinking that I could bend the hangers a little bit to raise to exhaust off of the axle, however, I'm starting to think that this will just cover up a different but related problem, rear end sag. I have ~170k on it, so the back coils could be showing their age. Do I need to replace the springs to truly fix the problem?