I don't think the pistons are forged though - I think they are "pressed" not forged. But are still better than standard cast pistons like the standard skyline ones.
Cubes - TheRB30 that run 10s usually do it easy dude to such a light car.
Seeing a Supra with a HKS T51r, on a standard 2jz, completely unopened, running 10's at 134mph is really amazing.
Thats at 30psi also. Been for a run in it, and it scared the shit out of me...heh heh. As I said before, look up "fus01" on youtube - I uploaded those videos for him. Very close mate of mine. (Currently in Rehabilitation, poor bugger was almost killed in a head on. Was driving his brothers ute to airlie beach)