take to muffler shop and have them loosen the exh. manifold/h-pipe nuts. they may charge like 10 bucks, but its worth it. the rest is simple, should just bolt right up
It helps to have some socket extensions available when you are trying to remove the header bolts, so make sure you have those. Also, a pipe cutter may come in handy. If you don't want to use a torch to get the cat-back off, you can either buy or rent a pipe cutter from Autozone. It looks like a pair of pliers with a chain hanging off one end; there are cutting wheels between the links of the chain. You just wrap it around the pipe, clamp it down, and move it back and forth many times until it cuts through the pipe.
The actual installation isn't that complicated, but it's not the sort of thing you want to begin and then stop because you need to run out and buy a tool. I found that removing the stock exhaust was the most difficult part. Installing the new pieces was fairly easy.
Besides all the other hints, make sure you give yourself enough room under the car to work (but be safe!). Use some WD-40 or similar stuff for the bolts. To get the passenger side pipe into position, I had to jack the body up on that side (in the rear) to give me enough room to fit the new pipe over the rear end. It's actually pretty easy to install even without a lift...