7. 1971 Pontiac Firebird Trans Am 455
The 1971 Firebird and Trans Am were practically identical to the 1970 models. They still represented one of the best muscle cars in the rapidly changing market. Unfortunately, 1971 proved to be the last true muscle car model year when buyers could get those high-powered and legendary engines.
Just one year after, 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 to appear in this model.
Since they lifted the GM displacement ban in 1970, all the divisions rushed to introduce big-block engines in their muscle cars. Pontiac did just that in 1971 for the Formula and Trans Am models. Although they rated the 455 V8 at 335 HP, most muscle car enthusiasts argued that they underestimated that conservative number. Even with the higher compression in the Trans Am HO version, that 455 V8 had the same horsepower figure. The real output was closer to 400 HP and with corresponding performance and top speed.