The fuel pressure is internally regulated to 58 psi eliminating the added expense and effort of purchasing and installing an external fuel pressure regulator - no separate return line is required because this module returns excess fuel right inside the tank! The 1964-1967 Chevrolet Chevelle, Malibu & El Camino Muscle Car EFI Fuel Pump module was designed as a direct replacement for your factory pick-up and sending unit. There is no need to purchase a custom EFI fuel tank. You can even retain the factory fuel hard line - just connect the outlet of the pump module to the hard line on your vehicle with EFI-rated fuel hose and hose clamps available in the Earls Vapor Guard line. This Muscle Car EFI Module includes a 255 LPH fuel pump and a Holley HydraMat. HydraMat is an amazing patent-pending fuel reservoir system that reduces fuel starvation issues that might otherwise occur while cornering, accelerating, stopping, traversing inclines, and during low fuel conditions.