This system uses a progressive controller that proportionally injects more or less according to manifold vacuum. Start and full points are adjustable for engagement and delivery curve, to match what the engine requires. High compression modified engines can gain performance through cooler intake charges and the large increase in octane and detonation suppression. It can also be geared towards fuel economy and using lower grades of gasoline. Comes with one 4150-style Carburetor spacer plate threaded for 1/8" injection nozzles, and a solenoid to prevent vacuum siphoning. System includes: SHO (Special High Output) Pump 1" Carb Spacer Plate Solenoid Valve to prevent Siphoning 3 Quart Reservoir Adjustable Variable Controller 2 nozzles cover a Wide Range of Horsepower All Required Hardware Needed For Installation