In terms of exhaust, I'd suggest going with the CS test/race pipe and the CS cat-back exhaust. If you go with the downpipe without a cat, there's a lot of work involved in getting it emissions-compliant if you need to. With the TP, you can slide under and swap it out for the stock 2nd cat in 10-20 minutes.
If you want a more reasonably priced route, check into the SLS or SU test pipe and the Magnaflow CBE. That should set you back $550 for everything if you shop around, maybe less if you find some of it used.