What happens in SD tuned cars?
Does the PCM calculate torque using the VE table?

Timing is an air quantity related function too (G/Cyl vs. rpm). How calculates the PCM G/Cyl? from the MAF signal? (G/sec).
And again: what happens in SD?

This is not about SD tuning, if it makes sense or not. It's just to know how the PCM works without the MAF signal.