The Edelbrock Victor Jr. LS3 cylinder heads are ideal for use in high performance street and competition engines that have reached their limit with a stock-style cylinder head design. Most aftermarket LS3 cylinder heads on the market today are simply stock head designs with larger ports. Our Victor Jr. LS3 cylinder heads are 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 heads when increasing the performance level of the engine. Changes include a 2.20+?G?-? 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. These cylinder heads also feature fully CNC+?G?G??d intake ports, combustion chambers and exhaust ports for consistency and improved performance. All of these changes make these cylinder heads capable of producing 600plus hp on an LS3 engine with stock rocker arms, intake manifold and exhaust manifolds. Installation Note: No.61339: Flow Numbers as tested by Edelbrock's SuperFlo SF-1020 flow bench @ 28in H2O