For -1 to be an 800, the test wouldn't really be in your favor, the difficulty of the questions could very likely throw off your perfect score. Even "hard" tests aren't usually -1 800 so expect really hard problems if you're hoping for -1 to be 800. And -2 is almost neeever 780 (almost).
Anyway, yea, I'm studying DH book 2 atm as last-minute prep... I need to bring my reading up !!