bmwman, the smt6 alters the load signal going into the motronic. also alters the VR signal if you want it to. they're supposed to be ok, have the same limitations as systems such as S-AFC etc.
i'd always liked the m44 throttle response and torque, figured a MAF would be quite nice. been in an m20 with MAF was good too. never found it a big difference though. the difference is more pronounced on a s14 etc.