Holley EFI Fuel Pressure Regulator 512-504-5 | 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. They feature a black bright dip anodized body and a clear bright dip anodized top for corrosion resistance and good looks. Holley Billet Fuel Pressure Regulators are available in a variety of configurations.