55-57 Chevy Hydroboost Kit with Chrome Master Cylinder and Brackets. 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 chrome master cylinder and firewall mount brackets. (Upgrade to a smooth or ball milled top master cylinder for and additional $20.00).