The Edelbrock 61339 Victor Jr. LS3 cylinder head is ideal for use in high Performance's street and competition engines that have reached their limit with a stock - style cylinder head design. Most aftermarket LS3 cylinder head on the market today are simply stock head designs with larger ports. Our Victor Jr. LS3 cylinder head is an all - new ground up design that incorporates subtle changes for improved flow and combustion. These changes were made to improve the limitations encountered in the stock cylinder head when increasing the performance level of the engine. Changes include a 2.20 diameter intake valve with a canted configuration similar to what is utilized in the GM LT1 Gen V engine. The intake valve change along with the unique port shape produce almost 400cfm peak flow. This cylinder head also feature fully CNC intake ports, combustion chambers and exhaust ports for consistency and improved performance. All of these changes make this cylinder head capable of producing 600 hp on an LS3 engine with stock rocker arms, intake manifold and exhaust manifolds.