If you keep the stock catback, which you should, you wont really notice a sound change at all.

ZZP headers are good, but they pretty much cost the most dough.

I paid 225 for my headers and run no cat. But I also had it tuned out.

Thats the other thing you'd have to know, if the set of headers you buy dont come with a cat, you will either have to buy one if you have emission or run one so you dont get a check engine light.