Progressive Intake Manifold - For Weber DGV, DFV, and Progressive Style Carburetors. Boost your engine's power and throttle response with theProgressive Intake Manifold from Appletree Auto. Specifically engineered for the popular Weber 32/36 DGV and DFV series, as well as other progressive-style two-barrel carburetors, this manifold is a favorite among air-cooled Volkswagen enthusiasts looking for a performance edge.