Turbo Charging

[NU2H2]

Sounds like you have a good handle on the stall idea. The turbo will react different to load. Just like towing a 7000lb trailer you have to produce more power to move the weight, hence more RPMs. The more RPMs produced the more boost produced when under load to a certain point that point being governed by the wastegate. The turbo will not produce boost when not under load ie neutral therefore turbos react different under different load conditions. More load more torque produced lower in the rev range. Stalling up the car with a stall converter is "loading" up the motor through the drivetrain.
Do I sound like I am rambling?