How do you know....
 

Here's the situation

Cat was rattling like a mofo a month of so back and then stopped all of a sudden. Had it checked out by Altech and they said it was fine. Didn't rattle anymore even when you hit it.

But now I get a lot of vibration through the car and stick shift and the exhaust tone seems louder than normal too.

I'm not getting a check engine light or anything.

What other way can you check to see if the cat is "gone" and in need of a replacement?

the simplest way to check is to do a emission test.

mine started rattling like that too but, the car bogged down so bad.. I dunno why yours would just stop..

Can you do that even tho you aren't scheduled for one?

I would suppose it'd be at the same cost too.

Yep you can schedule a test anytime.

How do you think people sell their cars e-tested...LOL.

my car slowed down drastically and i heard more of my AIR INTAKE then my exhaust!

the honeycomb filter blew right off and got stuck within the pipe!