620 horse power? That's what the upcoming 2013 Mustang Shelby GT500 might be getting. That is a full 40hp more than the Camaro ZL1 of which I'm sure Ford saw as a challenge to overtake.

MustangsDaily was the first to spot an interesting little tidbit in the recently negotiated labor agreement between Ford and the UAW. In a section outlining planned investments and changes at the company’s facilities, the listing for the Romeo Engine Plant includes a line that reads "The 5.4L Supercharged engine gets upgraded to a 5.8L." So one would assume the 620hp number is pretty accurate based on this?