Hi, call Power Brake Service at (800) 504 - 1060, and they can answer all your questions. If any of you are looking for a solution to the problems with the powermaster unit then check out the post ihave in the parts for sale section, it's titled Hydroboost brake conversion, it goes into full detail about how the unit works and why you should not get a vacuum conversion, why the powermaster doesn't work that well, and why it was put on your car in the first place