Abstract: A supplemental regulator used with a supercharged engine, a push rod, couples to a primary regulator. One side of a diaphragm of the supplemental regulator sees boost pressure of the supercharger. The other side of the diaphragm sees atmospheric pressure and fuel pressure sensed through the primary regulator diaphragm. A push rod couples the supplemental regulator diaphragm to a primary regulator diaphragm. Boost pressure above the diaphragm increases the force on a return bypass valve of the primary regulator. The bypass valve sees intake pressure and spring force that works on the top of the standard regulator diaphragm, and fuel pressure and that acts on the bottom of the diaphragm. When the supercharger is not providing boost, vacuum exists above the supplemental diaphragm, which lifts it and uncouples the supplemental regulator from the primary regulator. The primary regulator then takes over and maintains standard fuel pressure to the engine's injectors.