the gts-t is blessed with 4pots up front already. you would be suprised what a difference a good set of pads and braided lines make. If you want i would say get some 2 piece disks speced with a better vane design.
back home one of my good friends has an r33 gtst running around 300bhp, nothing spectacular but when we dropped a set of project mu pads on ...wow what a difference. Watch out if you dont have ABS and you upgrade the brakes, you WILL have to relearn your braking points and pedal effort.