Welcome to the club man! I'd definitely start with an exhaust set up. Don't be cheap and just get mufflers though, save and get a full system from headers back. Don't know your budget, but when I decided to do my exhaust on my sixxer back in high school, I didn't have thousands of dollars laying around. If you're looking for an affordable setup, I'd recommend PaceSetter Headers (LTs), an off road x pipe (doesn't really matter the brand) and some Flowmaster's. Obviously it isn't gonna sound like a procharged GT with a set of Borla's, but I think you'll be very happy. Like Skyline said though, gears and a tune are also great mods. I'd save my money on the intake though. I have one, but I think they are a bit of a waste of money.