I would think there's some major discrepancies in how far these combos have been wound out or how well they're matched. I'm guessing a major difference in octane, calibration quality, match of supercharger to engine etc. Even if there's say 3-500lbs difference you're still talking about the V having a combo that could make 11-1300hp on pump gas if there's enough turbo there to feed the engine. (based on my guess, those are actually conservative turbos.) It could also be that one engine is more (the V) or less (the Mustang) stock than is being let onto. The simplest would be the V is on straight pump and the Stang is on E85.
There may also be some power train discrepancies as well (10spd vs what's in the V) that would help the Mustang along. That said, I could also see where the extra gears would hurt at that power level.
Still a good race and a lot of power there.