Your other points are fine, but these 2, are just plain dumb.
You have ZERO clue how much your car will weigh after its all done. You are using a blanket range of weights for the Gallardo, and stock weights at that. You don't think someone who has a 1500hp gallardo didn't do weight savings too?
Also, you really don't think at the HP levels you are talking about, AWD doesn't help? Thats just dumb, really.