Cold Air Intake or Catback Exhaust?
Without a doubt, get a CAI and tuner package. If you have a problem, flash it back to stock before you go back to the dealer. Most of them don't worry about tunes, but you have to tell them not to reflash when it's there or you will have other problems [ask me how I know].
There are a number of great tuners out there, and you can also have it done at a shop with dyno, for a custom tune specific to your car, and that's your best bet
My 05 GT puts down about 340hp wtih my tune and mods and still gets over 20-mpg mixed with big tires.
You're lucky because you will be starting at a much higher baseline...