It seems actual operating compression is a hard thing to pin down. It also seems to me that it is the fundamental parameter determining power output through which essentially all performance enhancements have their effect.
The problem that I see is, what most people have to measure the variables involved cannot do it accurately. Kind of like flowing a single port on a set of heads, instead all of them. And even flowing it without the intake and carb, and without the exh header. And even doing that, you still cannot duplicate the entire true environmet in an operating engine. You cant get the pulsing an engine creates, or the momentum the temperature of the gasses creates. The best one can do is come close by "assuming" certain "average" numbers. Like the .6 mach number, and assuming airflow behaves exactly like a fluid in a shaped conduit. The results confirm the ideas are on the right track. But you can't really (at least in my opinion) point a finger at tthe result and say the positive end is only because of the theory. There's too many things that have come about by some person just rolling the dice and finding a new solution.