R33 what?
R33 GTS-25 : 280mm x 26mm (single pot sumitomo caliper)
R33 GTS-4 : 280mm x 26mm (single pot sumitomo caliper)
R33 GTS-25T : 296mm x 30mm (4 pot sumitomo caliper)
R33 GTR : 324mm x 32mm (4 pot brembo caliper)
R33 GTR VSPEC : 324mm x 30mm (4 pot brembo caliper)