Man, you guys are throwing around different efficiencies here. Volumetric Efficiency is a very very different story than Thermal Efficiency. Now I could be completely wrong in this, but I'm not exactly sure that thermal efficiency is pertinent to the over square question at hand. The reason I say that is because the real concern about operating at a high MP isn't necessarily the pressure in the manifold, but instead the cylinder pressure.
The quick and dirty, in my view, is that the argument revolves around operating a high MP with low RPM which results in a higher cylinder pressure working against a greater resistance. The reason I say volumetric efficiency is pertinent is because with higher VE, more air can be introduced to the cylinder. With more air, more fuel can be added to create a larger burn, and therefore more cylinder pressure. Thermal efficiency doesn't really come much into play for building cylinder pressure, or at least in my understanding.
Oh, and by the way, automotive VEs greater than 100 can be reached N/A.
