I had 280mm with standard setup. Then I stuck 288mm stuff with mintex M1144 pads and goodridge hoses. That massively improved braking, however I think it's down to the pads and hoses rather than an extra 8mm. Still, every little helps, and I believe the 288mm discs are slightly thicker too, so better heat dispersion. You'll want carriers, calipers, discs and pads. Most likely you'll need new brake hoses too as the 280mm uses hoses that screw into the caliper and the 288mm uses banjo screws.
