HOLLEY 12-879 Return Style Fuel Pressure Regulator 3/8 NPT Boost Reference – 1:1. Holley Billet Fuel Pressure Regulators are part of a complete line of fuel system products from Holley. They are precision machined from 6061-T6 billet aluminum for strength and durability. These regulators are adjustable from 4-65 psi and will handle both carbureted and […]