Bruno can confirm but answers are:
1. Correct...stock AFM was attached to a flow machine and measured for flow versus voltage. The controller for the new MAF was then calibrated based upon this voltage map versus flow.
2. Don't believe there was any restriction to the AFM installed to the flow machine.
Reason is...not relevant as the flap on a conventional AFM deflects given a certain volumetric flowrate through the AFM body. A cone or std. air box filter would simply reduce maximum flowrate into the AFM not inducing full flap angle for max flow and therefore would not affect actual calibration of flap position versus voltage to the DME.
3. Baseline AFM was Bruno's original stock 1989 AFM and likely had original factory calibration.
HTH's Jeff,
George