Search the threads... and yeah, taking off the cats will make it louder and add some power... but if you live in CA, you might wanna find out your emissions standards before doing so.
Yea pretty much what he said, take the stock h-pipe off and bash all the catalist out with a wooded pole and a hammer or something, just watch out for the 02 sensors if you have em. Or just pick up a cheap o/r h-pipe.
Edit: if you mean how do you take the whole pipe off it unbolts up near the headers/manifolds and down at the talipipes, it might be somewhat rusty could take a little work to get it knocked loose.