Back in the day, it was said that there was no replacement for displacement, meaning that the bigger the engine was, the better it was. Throughout the ’70s, numerous carmakers proved this theory wrong, including the 1971 Mach I Mustang that received the Boss 351 under the hood rather than the huge big block that all young street racers wanted. On paper, the large Cobra Jet should be the clear winner, but when put to the test, the Mach I with the Boss 351 sprinted from 0 to 60 in 5.7 seconds and ran the quarter mile in 13.6 seconds. The Mach I with the 429 CJ jumped from 0 to 60 in 6.4 seconds and sped through the quarter mile in 14.7 seconds. The Boss 351 is the clear winner on the track in real-life racing, even if the paperwork suggests otherwise