matt d,
Rustednuts is right...
The Hydrovac only makes it easier on the driver.
Chevrolet stated that if you have a hydorvac in the systen and put a test gauge in the brake line, when the gauge reaches 1000 psi the pedal is providing 35% of the effort and the Hydrovac is providing the other 65%.
I like having the Hydrovac's in my trucks...
Mike B
