Fuel Regulator before or after the Carburetor

Either will work on a return system. Put the fuel pressure gauge on the carb and tet each position, youll find they are about the same. Think about a wide open hose back to the tank, the carb will barely see any pressure. tighten the bypass regulator and the carb pressure at the inlets will go up just as though your opening the pressure regulator before the carb.