From talking to the Viper dudes here, Hal isn't supposed to give them more than 9 g's, sometimes it happens though. And, sometimes they are expecting 9 and Hal only gives them 7.5.
When they get more than 9, they have to go through the tapes frame by frame, they count the total number of frames that were above 9, then refer to some table with fuel weight, PA, etc to determine if it's an over-G.