I know it's a late post but if you know someone who can weld then a new exhaust would help. I'd cut the cat out of it and offset your o2 sensor in the exhaust. Depending on where you live you'd be fine doing it but if the car needs emission testing it might not pass. You could make your own cold air intake fairly easily which can save you some money. I've done a lot of them. All you'd need to do is find a pictures of one online and copy it. Rubber hoses are cheap and exhaust shops will sell you bent pipe to use. I'd think that both could be done for around $300 to $400 dollars. The muffler would be around $100, Air filter $50, Rubber hose and clamps $40, then the steel pipe. The exhaust pipe is cheap it's the bends that'll cost.
Thanks for the reply, I know that a more free flowing exhaust will add about 10HP to this car, maybe a bit more, but I don't want to sit in the middle of a constant drone. The road noise and wind noise from the car is pretty noticable as is without adding a louder exhaust.
I think I will end up going for a cold air intake for now, from what I have seen that adds about 10hp and get a stage 1 or stage 2 cams later when I save up some more money.