My experience in racing two late 80's/early 90's stang GT coupes was that, from a dig, it's the Stang all the way, both GT's pulled away from a stop quickly, only after 70MPH did they stop pulling. From a highway roll, like from 70MPH up to 140MPH, I pulled the GT's by about a carlength. This makes perfect sense to me, because the old 5L GT's fell flat on their face in the upper RPM's, they were torque monsters down low but had little high RPM performance (relative to the CSVT at least) to offer STOCK.
Then again, it's rare to find a stock GT Stang fox body these days. When I'm in my SS, I'm always wary, you never know what you're going up against when it comes to a fox body.