Holley 12-841 4.5-9 PSI Adjustable Bypass Billet Fuel Pressure Regulator with 3/8 NTP Ports. HP BILLET CARBURETED BY PASS FUEL PRESSURE REGULATOR. Street/Strip Carbureted Applications Two Port Adjustable from 4.5 to 9 PSI. Holley® Billet Fuel Pressure Regulators are part of a complete line of fuel system products from Holley®. They are precision machined from […]