Best AFR value

[odd boy]

It was noticed that in any modified tuning file under {B3168} part, the AFR is between 11.95 and 13. The reason behind that is to be in the max energy of combustion zone.

My questions:

1. What basis does the tuner follows to select the optimum AFR value for max power?

2. Why changes are added only to B3168 (PE mode) not to B3605 (open loop mode) as well? For example, if I added a cam to X car, the introduced amount of air will be different so fuel should be different, regardless, on open loop mode or on PE mode, is that right?