2003 Cavalier Catalytic Converter Rattling

2003 Chevy Cavalier, 5sp, 42,000mi, 2.2L eotec.

1st question:
Before I purchased the car, the owner prior put a catback exhaust witth tsudo headers on. The guy cut the catalytic converter off and welded it back on. It's always had a gurgling sound to it and I can't find a hole anywhere. Any idea of where this might be coming from?

2nd question:
I've owned the car for about 6 months now and within the past 2 days the catalytic converter rattles. Sounds like something inside the resevoir rattling around when the car is idle. When I'm driving you can't hear it but when I, say, stop at a stop light or pull into a parking space and stor the car at a dead stop it's really bad. I crawled under the car while it was running and held the catalytic converter still with my hands, gloves of course, and it stopped. Any idea if I need to replace the C.C? Thanks Guys!