The PFC allows access for many more parameters to fine tune I always thought. From my experience the stock s15 turbo is good for around 185-190rwkw depending on dyno (with injectors, fuel pump, FMIC and ecu tune). For an extra 15rwkw I don't think its worth it. Get a larger turbo (then your in 220rwk+ range and worth it then. ps try melbs15 forums. There is a lot of activity there and they seem to be a friendly bunch. You will also find many people selling cheap parts eg PFC, boost controllers etc. Good luck and enjoy the car.