To give background I have a 99 LS 4dr. and the muffler rusted off so it’s removed now. Now I have a very loud rattle coming from another part of the exhaust. I know it’s not engine sound cause it happens at random. My question is that instead of getting a whole new exhaust is it possible to get just a high flow cat and have some sort of turn down instead of getting a whole cat back system? Or is it better to get a cheap cat back system? Seeing as I like the current sound (minus the rattle) which is more better in your opinion?