FUELAB® 515 Series Fuel Pressure Regulators are designed with performance and flexibility in mind. They accept port style and non-port style union fittings without interference. Several configurations are available, supporting carbureted applications as low as 1 PSID to fuel injected applications up to 125 PSID. The 515 Series Fuel Pressure Regulator has a -6AN return port located on the bottom. Fuel Pressure Regulator Features. We carry all Fuelab products so if you can’t find what you need, please call.