I get a rattle at low rpm's. I looked around and hit the cat a couple times and it doesn't sound like anything was loose inside. It actually sounds like its the muffler. I've never heard of a muffler getting clogged like a cat does but here's the link to the video, see what you think (the visuals suck, audio is all that matters):

 

My cat's rattling like crazy and it's definitely a different pitch than that. Mine's much higher. Sounds like gravel in the pipe. Yours sounds almost like a loose slip joint on the pipes, or a muffler tapping the frame.

 

That's what I thought but it doesn't seem to be hitting anything. It literally sounds like its coming from inside the muffler.

 

I suppose one of the baffles inside could have come loose.

 

I'm not too worried if it's the muffler, I was planning on getting a cat back soon, but I do have to pass an emissions test coming up so I'm just trying to make sure that it's not the cat that's going bad.

 

When my cat failed it sounded like the other poster described.

 

Alright cool. thanks guys.