Hydroboost Kit for GM A & F Body Cars. Hydroboost brakes are a great upgrade over manual or vacuum power brakes. These hydraulic assist brakes work off of your power steering pump and are more powerful and compact than a vacuum assist system. Hydroboost brakes work perfect with blown engines and engines with low vacuum. Kit includes the hydroboost, a polished aluminum Wilwood master cylinder and firewall mount brackets for 1964-1972 Chevy, Pontiac, Oldsmobile and Buick A & F body cars.