In the map software the peak stock maf flow 0-5v scale works out at 673kghr which works out at 186.9444gs or around 240bhp on a dyno reading.
The bigger maf is used to rescale the whole map to allow for a greater scope for performance, at the same time is the correct sized injectors are used to match the maf % gain then global constant for injection on tiime vs air flow will be correct, which makes the mapping easy by just rescaling the the load axis on the timing maps. It only on the AGU we need to work this way.