The RUF RT12 R already ran huge 15" front and 13.5" rear diameter ceramic disc ( ventilated + cross drilled ), with 8 piston front and 4 piston rear aluminum monoblock caliper augmented by BOSCH 8.0 ABS system, it's beaten recently by 2015 RUF RTR with 16.1" front and 15.4" rear ( at least on a RUF car )
Maybe replace the Michelin Pilot Sports Cup with stickier tire is better/simpler/cheaper way to shorten braking distance
Oh, for top speed, with shorter final, it tops at 217 Mph ( for vanilla RT12 with 650 HP, 6th gear ratio 0.75), there are 2 final drive options, the taller one allowed to reach 225 Mph ( what Ruf said, but RT12 R should be able to reach it with 750HP/709lb-ft / 1.3 Bar of boost )