THE STi is fitted with a Brembo-manufactured braking system that includes "Super Sports" ABS and Electronic Brake force Distribution (EBD). The front brakes comprise 326mm diameter by 30mm thick ventilated discs with four piston callipers - there are two larger 46mm pistons and two smaller 40mm pistons acting on each side of the disc to promote consistent brake pad wear across the length of the pad. The rear brakes have 316mm diameter by 20mm thick ventilated discs with two piston callipers (each piston measures 36mm). The STi's Super Sports ABS system controls rear braking force individually - via input from a lateral G-force sensor - whereas standard ABS jointly controls both rear brakes to the same braking force. In a hard cornering braking test, under the same conditions, the standard ABS set-up will produce a longer stopping distance and greater cornering understeer than the high-level system in the STi.