If you're looking for an easy boost in performance and don't care as much about the JCW Pro exhaust that comes with the tuning kit, look at doing a power module.
There are a few out there, most between $300-400 and they'll net you about 20-40 extra HP and ft-lb of torque. Burger Tuning makes one, NM Engineering (that's what I have-recommended), Remus, plus a couple others I'm probably forgetting. These take about 15 minutes to install and can be removed just as easily.
There's several threads about these, just search around.