Personally for a tS, I would stick to a more bolt on solution like a supercharger kit. This is a car you may think you'd like to keep forever but what if in a few years, toyota and subaru come through with a factory forced induction car and you want to upgrade? Removing a bolt on solution, selling the kit and selling or trading the car in as close to factory as possible would likely be easier and potentially get you more money from your initial investment. Something to keep in mind.