Basically, the first step in n/a tuning would be your breathing. Intakes, i believe the gruppem has the kevler intake box. You do have a lot of choice in terms of exhaust. You have tubi, larini, quicksilver, b&b, and platinum motors exhaust which is spengineering stuff. Try to avoid hamann exhausts. Otherwise, get whatever sounds best for you. As far as the horsepower is concerned with the exhausts, they run the same, which is a little. Either replace the cat or get sport cats. the fewer number of cells wiill definitely get you to breathe better. Please specifically state how far you would want to take your car to. Not only you could n/a tune your car or be crazy and get forced induction system. Are you willing to port out your motor and change all your cams, throttle, valve, coating, and railing? what kind of horsepower are you expecting. I would not touch anything other than your exhaust and filters on the 06s. Perhaps getting a imsa kit will make you flash more. Want something faster on a straight-a-way, get a murcie. Its money money money once you touch your motor.