Can't answer that double zero... I'm just a humble PPL and plane spod who has had the privilege of riding backseat in a Macchi with the RNZAF, and a Hawk with the RAF through the Mach Loop.
Needless to say... I was also allowed a little fly myself on both occassions
The other trick they do (which us humble bugsmashers never will) is rolling inverted at very low altitude to go over the top of a hill (we did this in the Macchi) - presumably to keep as low as possible and avoid a red-out through a high G pushover.
Any knucks... is there a name for this manouvere?