11. The 408 was run on the engine dyno with a Fast LSXRT (truck) intake and 102mm throttle body. Also present was a set of 1 3/4th-inch headers, 42-pound injectors and Holley Dominator EFI system. Run with the stock 5.3L truck cam, the 408 stroker pumped out 449 hp at 5,100 rpm and 522 lb-ft at 3,900 rpm. Torque production exceeded 500 lb-ft from 3,500 rpm to 4,600 rpm.