We have exchanged the rear brake callipers for the stronger C4 4-piston versions. All parts have of course been overhauled according to DTW standards. The brake booster does not get its negative pressure from the intake manifold as in the series cars. When the flaps are open on the single throttle valve system, there is low intake manifold pressure and thereby brake power loss. Therefore, an electric vacuum pump with control unit is fitted which ensures constant negative pressure. Even if, like Walter Röhrl, you ever press the accelerator and brake pedal with one foot simultaneously, this car does not only accelerate excellently, but also decelerates with ease.