The S65 V8 in the E92 M3 is mafless to begin with instead using a MAP (mass air pressure) sensor to detect intake airflow. In a forced induction setup the MAP sensor can detect air pressure in the manifold which certainly is useful. A MAP sensor will traditionally measure vacuum and pressure.
The MAF sensor on the other hand senses air flow. To break it down however much air passes by the sensor is what it reports. In certain situations the air flow may not be the exact CFM (cubic feet per minute) of air going into the motor which can complicate MAF tuning.
Both approaches are used and there are pluses and minuses but since a MAP sensor uses the actual pressure instead of flow even if a boost hose blows off or there is pressure loss a good tune should be able to compensate better than a MAF setup in such a situation. Additionally, the MAF may pose a physical restriction in the air intake tract. Throttle response also can be improved with MAFless tuning.
VF-Engineering made the switch to an in-house MAFless tune tailored for their intercooled kits (the entry level non-intercooled supercharger kit is still MAF tuned as BimmerBoost understands it) and the results have been positive. Why is this important? Because it goes to show how marketing quickly changes. This was VF-Engineering's stance when they were tuning with the MAF sensor:
'Our supercharger competitors do not run a MAF because tuning with a MAF on the M3 is like trying to hit a moving target so they remove it and call it Alpha-N which to some sounds like a special "added feature". In actual fact, Alpha-N is a "safety mode" designed by BMW as a back up for when the TPS or MAF fails. VF uses a more reliable and forced induction proven, Hitachi MAF and re-calibrates the ECU to operate the vehicle smoothly and with full control of part throttle fuel trimming and WOT AFR control. No other tuner has done this to our knowledge. The Hitachi MAF upgrade is becoming a growing upgrade amongst the Porsche TTs also.
In order to run the S54s MSS54HP ecu in Alpha-N mode without a CEL, you have to delete certain aspects of the ECUs error reporting functions. Removing a MAF from your M3 will prevent it from operating dynamically to atmospheric conditions. For most part, the car will be operated on a locked set of maps which are pre-determined by the tuner. With a MAF your car will be able to adapt and use all the ECU dynamic controls. Running in Alpha-N may be well suited for very high power (1000hp) or track use, but we prefer not to run our production kits in safety mode.'
Heh, how things change based on what you sell. What you read above from VF-Engineering is simply marketing spin. The VF-Engineering kit is not using a MAP sensor but an Alpha-N tuning approach based on rpm and throttle position. They are doing what they advocated against at one point. You need to have a good tuner for this approach (which VF appears to have) and there is a downside to elevation changes as the motor will not know air density has changed. However, it should provide sharper throttle response and a better tuned motor for boost. It should also provide for a more accurate tune in the conditions for which it is tuned.
Video with dyno below, 471 wheel horsepower: