7. 1971 Pontiac Firebird Trans Am 455
The 1971 Firebird and Trans Am were practically identical to the 1970 models. Yet, they still represented the best muscle cars on the rapidly changing market. The 1971 Firebird proved to be the last true muscle car model year that buyers could buy high powered, legendary engines. Just a year after that, in 1972, the horsepower ratings started to go down.
But the biggest news for the Firebird/Trans Am lineup was the introduction of the mighty 455 V8, the biggest engine ever to appear in this model. Since they lifted the GM displacement ban in 1970, most manufacturers rushed to introduce big block engines in their muscle cars. And Pontiac did just that in 1971 for their Firebird and Trans Am models.
The 455 V8 had 335 HP, but muscle car enthusiasts argue that they underrated that number. Even with higher compression in the Trans Am H.O. version, that 455 V8 had the same horsepower figure. So the real output was closer to 400 HP and with corresponding performances and top speeds.