That GT was the same car that was used in the Motor Trend road test, when it went 10.97. The mods consisted of the Kenne-Bell supercharger overdrive unit, the Accufab throttle body and Inlet Sleeve, a Borla exhast system and some computer modifications. The HP stock before any mods was 531 at the rear tires and 670 with the mods. We have seen stock GT horsepower anywhere from 510 to 531. The 670 HP is a de-tuned number. Our policy when working on customer's GT's is to be conservative, whether it's with blower boost or with fuel-air and timing (computer re-flashing). We assume that the customer will still use regualr pump gasoline at all times. When we ran the drag strip up in Canada that time (10.97) the car had been used on a road racing course all day for a TV show, and so we didn't want to push the envelope. There is no reason, actually, to modify one of these cars past their practicality point. As a street machine, with the A/C running and the CD's craniking out some tunes, and just having some fun, there is no logical reason to try for 20 pounds of boost and a lean mixture, just to scare your friends.
If we wanted to, we could have 900-1000 HP at the rear tires, but what would we do with the damn thing? Of course, now that I think about it, the silver M/T test car (the 10.97 car) is sitting here right now and it has dual turbochargers on it, and we all know how logical THAT is.