Knowing how to drive eliminates the need for a ridiculous brake kit unless you track the car or don't know how to drive.
Best Upgrade I've ever done is a brake booster/steel lines/fluid/pads...cost less than 500 bucks and the brakes respond much better and operate wonderfully and don't heat soak worth a damn. If you have an STi then you shouldn't even be playing with the idea of replacing the pistons...rotors I could understand. I may get some floating rotors just for the benefit of less rotational weight etc but some of these HUGE brake kits are so funny to read about! Subaru's usually weight somewhere between what? 2900 and 3500 pounds with the driver in the car? I am always amused when I see an 8 thousand dollar brake kit on a subi...just a waste.