Related Photo Galleries
Mast’s LS3 head castings are available in three different trim levels for small- (3.900 to 3.930), medium- (4.000 to 4.070), and large-inch bore (4.125 to 4.200) motors. The small-bore heads have 253/89cc ports and 2.080/1.600-inch valves, the medium-bore heads utilize 256/89cc ports and 2.165/1.600-inch valves, and the large-bore heads offer 270/87cc ports and 2.200/1.600-inch valves. Prices for a fully assembled set—which includes factory GM rocker arms and Mast rocker stands—start at $3,600. That’s not cheap, but there’s no denying the tremendous volume of air they move.