If you do a search you can find a plethora of information on exhausts for our cars. But just to save you the time...
You have four basic options. In no particular order they are:
1. Buy a magnaflow muffler and have it welded to your stock cat back piping.
2. Solo-Performance offers a few different configurations as well as a high flow cat.
3. Turbokits.com has a single cat back system as well as a high flow cat.
4. Ark Performance has a single cat back system which is very shiny and priced as such. They also have what they call a "test pipe". I believe it is a cat-delete but I'm not sure.
The last three have vendors here on the forums that you can talk to for more information about them. Like I said, a simple search should provide plenty of opinions on ALL of these options.