FULL DYNO RESULTS-SAME GT45 TURBO. Turbo 4.8L LS vs Turbo 454 BBC-Who Wins? Check out this test comparing a 4.8L LR4 to a 454 BBC, each equipped with the same Ebay GT-45 Turbo. Include are the hp and torque numbers for both moors, both NA and turbo, as well as boost and back pressure. How high did that back pressure get?