Ol' Blue's magnum swap

I finally got a chance to pull a clean run against my buddy in his 2012 Shelby GT500 last Saturday after work. He's got long tube headers, and Flowmaster cat backs, I'm figuring somewhere around 575 at the crank. I still have the open 7 1/4 rear end and skinny little 14 inch tires so we ran from 45 up to make it a little more fair. I still left a hundred foot black mark, but we were neck-and-neck until 120. I'm still not quite sure what horsepower that suggests I'm at but that Dart is about 600 pounds lighter and the GT500 was just barely pulling on me. At least my buddy can't talk crap about my car anymore LOL... Not quite as slow as he thought