When you trying to extract every ounce of performance from your carbureted LS combination, our new race bred Split-Design Single Plane intake manifolds make it possible. Typically found only on the most expensive race intakes, Holley’s Single Plane Split-Design intake manifold allows you to directly access to the internal plenum and port surfaces! Custom porting and port matching is now that much easier! Now you can reach all the difficult to reach areas easily with a die grinder. These fit all GM LS Gen III and IV engines equipped with LS1/LS2/LS6 cathedral port cylinders. Not only are these lighter than other split manifolds, we’ve also added extra material at the base of the runners for nitrous or methanol nozzles’. By incorporating shoulder bolt locators and a captured o-ring seal… reassembly is easy and precise. The single plane design provides optimal performance across the entire RPM range providing maximum performance up to 7000+ rpm depending on engine combination. The 4150 style square bore flange accepts carburetors or throttle body EFI units. Vacuum ports are built into the carb flange of the manifold for easy vacuum line hookup. Holley’s new Single Plane Split-Design intake will allow you to take your performance to the next level.