Spectre's Down the Middle (DTM) Air Intake Plenums are fabricated from high quality polished aluminum sheet metal. This ultra-low profile plenum fits carburetors and TBI throttle bodies with a 5-1/8 inch inlet and requires a minimum of 2-1/4 inches of clearance between the carburetor and the hood. Spectre's DTM air intake plenums feature a 4 inch single inlet that is designed to match up to Spectre 4 inch tubing, filters, and accessories allowing you to design your very own custom cold air intake system. Spectre s Down the Middle (DTM) Air Intake Plenums are fabricated from high quality polished aluminum sheet metal. This ultra-low profile plenum fits carburetors with a 5-1/8 inch inlet and requires a minimum of 2-1/4 inches of clearance.