This low vacuum bypass is a direct replacement for the LSA / LS9 OEM bypass. It is designed to open and function properly on low vacuum engines. Stage 3/4 camshafts in LSA/LS9 engines do not pull enough vacuum to open the OEM bypass valve all the way. This results in poor gas mileage, poor driveability, and decreased supercharger life. The Kong low vacuum bypass valve is the first and only direct replacement option specifically designed for these engines.