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With the double diaphragm booster fitted, and with the vacuum back at 16 inches with the motor at idle, the front brakes showed almost 700 psi. A huge improvement! This compares well with Classic Performance Products' own specs which state that a dual diaphragm 7-inch booster with 23 inches of vacuum will provide 175 psi of "free pressure" (the pressure the booster can provide, as opposed to "manual pressure," that exerted manually on the pedal without the booster) with 100 pounds of weight applied to a pedal with a 7:1 ratio and a 1-inch bore master cylinder. The rear brakes now both showed 650 psi, proving that the proportioning valve was working. Up to 500 psi, the front and rear will be supplied the same pressure, then over 500 psi, the rear will get approximately half of what the front is supplied.