How do you know if your cats are bad?? i have a rattling noise so I took off all my heat shields and i still had a rattle, i got under the X today and was banging on things and notice the lower drivers side cat rattles like hell when I bang on it...

Sounds like a good enough indication to me. I'd hollow that thing out and put it back.

is it true that a cat converter can make a rotten egg smell and iff so wtf is that...????