ECUTEK specalise in Subaru & Mitsubishi remapping, they do a convertion by serial port connection which remaps the cars standard ecu, so theres no changing things or pulling the car apart to do it, just a laptop plugged in to a serial port in the car.
Ecutek developed quite a bit of the Ralliart & Prodrive stuff aswell, so no need to go to Japan
the dentist uses Ecutek amongst his other brands