Cat what?

I want to replace the magnaflow exhaust that is on my car at the moment. I have read that you should get a cat-back system. What do you get in this system? If I already have a high flow cat-converter can I just relplace the muffler and get the same out of it?

Thanks

Is the magaflow a 2.5" or 3" and is it a cat-back?

i think 3, and as far as i know it is not a cat back

Then what is it, if it's 3" and not a catback. Is it just an axleback or just a muffler.

Cat back just means everything behind the catalytic converter or from the cat back.