Exhaust set-up

Fellas I'm kinda new to Grand Prix's. I just got mine a couple weeks ago and it has been in the shop ever since. It's finally done this weekend (I hope) and once I get it back I'm looking to give it a little extra HP,torque and fuel economy. The obvious way to do this is exhaust and intake but I'm not sure about the best set-up for the supercharged model. I've only got enough money to put on a high-flow cat and a cat-back system. I have no idea what these cars like. I don't know the engine characteristics yet or how much boost the charger pushes. Any suggestions on a good, but not too loud, exhaust set up?

ubend delete.
high flow cat
3" Down pipe

You dont need a catback system, just get some mufflers.