Those are really neat cars. I worked with a guy that bought one in 2003, and had the opportunity to buy it a number of years ago...I probably should have.
Those motors are significantly different from the standard Ford Modular V8. They are 4 Valve DOHC, versus the 2 Valve SOHC used in the regular GT. Plus I believe they are all aluminum, whereas the GT used a cast iron block and aluminum heads. They have higher compression and I believe the horsepower numbers were actually underated on those.
At any rate, that is a REALLY cool car and it is definitely a collectible. Make sure he takes care of that thing, it's a special one!
Oh, and the interiors are really cool on those. Comfort Weave seats, and retro instrument cluster. COOL!