When you upgrade to a 3 bar OS does it completely disable the MAF and not even let you read it as a sensor? If that is the case does it disable everything that uses cylinder airmass and airflow, or does it calculate it somehow?

I have an 01 Silverado 5.3 with a small turbo and cam. I upgraded the P01 to a 3 Bar OS. I still have the MAF hooked up before the turbo, but used a breakout harness to relocate the IAT to after the turbo. There are a few things I'm having trouble with:

1. How does it calculate cylinder airmass for spark advance/retard and other adjustments? All of the built in calculators return 0 when scanning. I tried creating a user math version of "IAT/Inj/AFR/MAP Cylinder Airmass" and using the 3 bar MAP sensor value. It does return a value but they never drop below the 1.20 gram max the spark tables use.

2. Does the ECM calculate Airflow somehow for all the adjustments that use that? Specifically I'm looking at the "Cylinder Charge Temperature Bias vs. Airflow" table, though I'm sure there are other things that use it.

3. Can the MAF be read at all even if its not being used? Mostly I would like to read it to adjust the "Base Running Airflow" table for idle.