A new power brake booster and master cylinder are included in the kit. The new cylinder uses a larger internal-bore diameter to move more fluid for the increased volume of the new twin-piston calipers up front and single-pistons out back in place of wheel cylinders. The bigger booster will generate more assist to move all those pistons quickly. Clearance to the strut tower is minimal. In fact, the instructions advise that '90-and-earlier Mustangs may require that the tower be "relieved" with some hammer blows to allow installation.