Style chooser

I just purchased a toyota matrix '04 XR. I would like to get a cool air intake and or a exaust system. I would like to know what to purchase and in what order should i purchase them and or any other car parts like pulleys and such. Where i should purchase it? Should i have someone else install it for me or should i do it myself? I'm new to all of this and would like to make the best of my car. Also, i just purchased a new car radio (Alpine) and had it installed... What do you recomend for a...