AC Schnitzer l'ha fato con il setup 'stradale' :
For fast acceleration on the road and track, safe braking is essential - so the second front brake was an important part in the engineers' specifications. The fully adjustable upside-down fork from WP Suspension with diameter 50mm brings sufficient rigidity
and provides a mounting for the 2nd brake. The 4-piston callipers of the R 1100 S BoxerCup Replica are fitted with adapters and grip the corresponding 320 mm diameter brake discs. They are activated with a 17mm radial pump from PHOENIX, which is matched by the 16mm radial clutch pump.
http://www.ac-schnitzer.de/en/bmw-mo...schnitzer-hp2/