was a common practice of American car makers; and that the engine actually produced well over as delivered from the factory. Indeed, the AHRA ASA (Showroom Stock Automatic) Class record-holding Chevelle LS-6 for the 1970 racing season posted a best-of-season trap speed of , which suggests something on the order of 350 "as installed" (SAE Net) HP for a car-and-driver combination. Indeed, Super Chevy Magazine conducted a chassis dyno test of a well-documented, well tuned, but stock 1970 LS-6 Chevelle and recorded 283 peak HP at the wheels – a figure that lines up quite well with the previously referenced 350 SAE Net HP figure. An even more powerful version, producing and , of the 454, then dubbed LS-7 (not to be confused with the modern, mid 2000s, 7-litre Chevrolet Corvette engine that powered the C6 Z06, which is an LS7). Several LS-7 intake manifolds were individually produced and sold to the general public by a few Chevrolet dealers as optional performance parts. The LS-7 was later offered as a crate engine from Chevrolet Performance with an officially rated power minimum of gross. In 1971, the LS-5 produced and , and the LS-6 option came in at and . In 1972, only the LS-5 remained, when SAE net power ratings and the move towards emission compliance resulted in a temporary output decline, due to lowered compression, to about and . The 1973 LS-4 produced and , with and gone the following year. Hardened valve seats further increased reliability and helped allow these engines to last much longer than the earlier versions, even without the protection previously provided by leaded fuel. 1974 was the last year of the 454 in the Corvette, although the Chevelle offered it in the first half of the 1975 model year. It was also available in the full size Impala/Caprice through model year 1976. 1970–1976 Chevrolet Caprice 1970–1975 Chevrolet Chevelle 1970–1975 Chevrolet Monte Carlo 1970–1975 Chevrolet El Camino 1971–1975 GMC Sprint 1970–1974 Chevrolet Corvette L19 General Motors introduced EFI in 1987, which was found on GM C1500 SS, C/K2500 and C/K3500 trucks. The 454 EFI version was rated from to and from to of torque. The 1991 through 1993 454SS made 255 HP at 4000 TPM and 405 TQ at 2400 RPM thanks to dual 2.5" catalytic converters. All other versions, including the 1990 SS, made 230 HP at 3600 RPM and 385 TQ at 1600