My car came witha DC sports cat back and I have a nasty rattle and i’m pretty sure it’s in my muffler. All of my piping is just fine I was just going to weld in a new muffler. But I don’t want anything louder than what I have…if it was quieter I wouldn’t mind too much , but a loud exhaust is annoying to me bucause I spend some time on the highway.
You should try the google exhaust, I heard it was really good at solving problems like the one you’re having.
I personally like the rsr ex mag its quiet and has a nice tone
check and see if your cat or any where else has a heat sheild. If it does just bang it with your hand. When you find whats rattaling, grab a couple hose clamps and wrap them around the loose shelid.