It's very common for the cat's to get blocked, as XplodEd EA said, the internals break down a block the cat. If you're real unlucky, they can actually break free and travel into your muffler. Then you'll have a nice, loud rattling sound upon decelleration - NOT PLEASANT! When I bought my EA, the cat was stuffed, so the first thing I did was to rip it off and replace it with a high flow cat - and even with an otherwise standard exhaust, you could feel a big difference!
As for the rest of your exhaust (cat-back), have you done any major mods to the engine??? If not, then I'd HIGHLY recommend going for a 2.25" exhaust with a single high-flow muffler. On a standard EA, 2.5" is too big. 2.25" will give you a noticable increase in power at high revs, but more importantly will give you a large increase in torque in the sub-2000 rpm range (one of the EA's major downfalls).