It all depends deffinilty a new intake with an open cone, if ur thinking on going the turbo route then there is no point in headers cuz u need to keep the stock ones, if not go with the doug thorley, if u plan on driving the car hard u might aswell put stronger pieces in your tranny because it will blow out on you. There really isnt a hole lot. Get will overkill tune and the gxp has displacement on demand get that disabled, it dosnt change mpg's hardly at all, and it wont burn any more oil. If ur not getting headers go with a better downpipe and if u want a sexy exhaust note do a cut out before the catilitic converter. A tranny cooler will help your transmission out alot. If u have any question about going turbo let me know i have gxp with turbo kit from cartuning aswell
