I have a local muffler shop that is like the In-n-Out of exhausts. Cat, mufflers, and tips is all they do. They can install new high-flow cats and new mufflers to your existing piping if it is decent. They also do their own piping when needed. I have had them work on my miatas. With a high flow cat and magnaflow muffler it had much better response, beautiful sound, better gas mileage, and passed emissions with flying colors. All for $250.
I mention this to encourage you to check locally to see if you have any shops near you that could do the same thing. It is much cheaper option than the new exhaust kits. Although they are pretty easy to install yourself if you can get under the car.