R33 GTS4's were all N/A's the poor buggers.
In the conversion, you can also use holden rotors drilled to the right PCD if you can't source R33 GTSt rotors, they're almost identical in dimensions. Also if you're getting R32 GTSt front calipers, make sure you get the Type M ones as they're 4 pot, instead of the regular 2 pot. R33 GTS25t's should be all 4 pot.