My 78 Z was a 5 spd car and brake system worked great until i converted to LS1 auto . It required more foot pressure to keep it stationary , in drive , at stops . It braked fine . With 10" booster , it feels like the car is neutral and slows the car down MUCH faster . Could have been a bad MC , but it worked as good as my 83 ZXT before the conversion . I Think the 10" was disigned for auto car .