Shawn hit the nail on the head. I have a 27 and they are not the most aero cars out there. MPH is king in the super classes and with the same motor combination in a 27 as opposed to say a 2010 vette body you would easily see 2-3 mph difference. Probably more like 5, but I don't have any data, just my WAG at it. As soon as I have opportunity I will be going to a later model vette body. I would like a 57.
Curtis