455 horsepower Pontiac GTO, manufactured in 1972

The 1964 Pontiac GTO was the first of its kind, and the 1972 Pontiac Firebird GT insulted its reputation and effectively ended the classic 

muscle car era. In 1972, the 400ci engine was detuned to a 250-horsepower weakling, and by some miracle of science, the 455 made

the same underwhelming power, and the GTO went back to being an option package instead of its own model. High Output 455 models, 

which increased power to 300 hp, are very uncommon and cannot be swapped with standard models. A Hellaphant switch is required for 

the standard GTO 455, since the original muscle vehicle should have the most powerful muscle car engine available at the time.