For starters, definitely 3" all the way back for the most performance. There are several ways of doing this. The cheapest route would be to buy a 3" 02 housing and downpipe and then have an exhaust shop build you a 3" cat back. This option could be around 500 bucks if you play your cards right. The turbobacks out there are good options as well, but you'll most likely end up payin a couple hundred bucks more...just depends on what'cha wanna do. Take a look at the exhaust sound/movie clip thread and see what suits your needs in there, lots of different exhausts to listen to.