I owned a VF34'd WRX, okay? Basically the identical setup to yours, so it's not like I'm a newcomer to the pull of the car. I'm just saying that the numbers don't really seem to support a "walk away" win by a VF34 modded WRX, at least not from a roll. Your best run is with a 103mph trap, according to your sig. I wouldn't be a bit surprised if guys in new GT's aren't getting pretty close to that at the drag strip. Heck, Car and Driver trapped 103mph in it. From a stop, the WRX will probably win, depending on drivers, etc, due to the AWD launch.
I like Subies as much as the next guy, but I've got to give the 300hp V8 (with flatter torque curve and no AWD drivetrain loss) it's due.
I know I'm doing a bit of magazine racing, but I'm sure a quick trip to the Mustang forum would back me up.