Single Plane EFI Split-Design Race Intake Manifold- GM LS1/LS2/LS6 EFI Single Plane Split-Design Race Intake Manifold Fits All GM LS Gen III or IV Engines Equipped with LS1/LS2/LS6 Style Cathedral Port Cylinder Heads HolleyThe Ls Race single plane intake manifold was designed for hi performance racing engine applications, 5. 3 to 6. 2+ liter displacement, and maximum engine speeds of 6000 7000 rpm, depending on the engine combination. This single plane design provides optimal performance across the RPM spectrum while providing maximum performance up to 7000 rpm. ? As Cast Runner Cross Sectional Area 3. 5 in2 at the runner entry tapered to 2. 9 in2 at the flange exit ?