- When I am on the throttle it almost sounds like a piece of my cat is broken and rolling around in my exhaust. It only makes this noise on low rpm's. If I go over 3.5k the noise will go away.

A friend at work said my resonator may be falling apart internally. He recommended a take a big screw and drill through it to keep everything tight. The noise if fucking annoying halp h:

 

What kind of car?

Rattling heat shield on the catalyst?

Some Hondas have problems with a 'buzzing' A-pipe (from the manifold to the catalyst). It's a pipe-inside-a-pipe & the inside pipe can buzz against the outer one.

 

or by a slight chance it could be a broken-down cat.

I had a nissan stanza that had similar symptoms and it turned out to be the cat.

can't say for sure though..