This Regulator is designed for turbo or supercharged engines. As boost pressure increases, more fuel is required by the engine. This regulator features a boost reference circuit that adds more fuel in relation to boost pressure. The inlet and outlets are 5/16" and a jam nut is supplied for special threads on the bottom to ease mounting to a bracket. These rugged Regulators are free standing so they don't have to be mounted directly to a fuel rail and can be installed in any position. Fuel pressure is set with an adjusting bolt and is locked in position with a locking nut.