The MC/Booster set-up sold by all of the vendors are made for the light duty trucks and most use a Corvette MC with about a 1-1/8" bore. Our big trucks require a larger bore (1-1/4" or 1-1/2") to move the correct amount of fluid to the wheel cylinders. If you use a MC that's smaller the pedal will travel farther (closser to the floor) to fill the wheel cylinders reducing your margin of safety.
Mike B
