Buick stunned the entire world in 1970 when they debuted the Skylark GSX Stage 1, one of the most tempting and full muscle cars at the time. With a 455-CID 4-stroke carbureted V8, the GSX Stage 1 was capable of producing 360 horsepower, however it's worth noting that these figures were published by Buick, and many believe that horsepower for the Stage 1 was really higher.