 If no valve were employed and both compressors were merely routed directly to the intake manifold, the supercharger would blow backwards through the turbocharger compressor rather than pressurize the intake manifold, as that would be the path of least resistance.Thus a diverter valve must be employed to vent turbocharger air until it has reached the pressure in the intake manifold.Complex or expensive electronic controls are usually necessary to ensure smooth power delivery.