KA24DE- Hollow cat makes worst noise ever?

[Kingtal0n]

Yeah I saw the upper cat. i thought the car had two. So how the heck was it making such an awful racket? Maybe the problem is deeper in the exhaust system, and the hollow cat was amplifying the noise? I know there is some kind of "resonator" but I've got no clue what it does or how it works. Could that be bad making a bad noise? I mean I know what the term resonate means, within reason. I assume it has a noise cancelling effect based on common frequencies produced by the engine during normal operation. I also assume they've "tuned" it somehow, perhaps with a special series of shapes. But I've never looked into it and have no experience with it.