Okay, well after compiling all the info that people are "sure" about.....it seems that the fronts and rears are larger on the GSX, than the GST, GS, and RS.

I know for a FACT that the front rotors are definently bigger and the calipers are dual piston.

Also keep in mind, you don't necessarily have to swap out the rears. The rear brakes don't do the amount of work that the fronts do, so it would be more beneficial to swap the fronts. Swap the rears if you wish, as well. You won't really need any more stopping power if it's basically a street car. The GSX front brak setup should be plenty.