Basically what this is saying is that +.34 Psi @ 14.21 psi = + 17hp difference IN FAVOR of ram air. Which is good. However air is incompressible at speeds below 230mph IE: 14.7psi @ sea level + xx value.

So the ram air does work at bringing the PSI close to atmospheric pressure of 14.7, but will not cross that threshold until ground or airspeed reaches at least 230mph.

So myth confirmed, to a point. My apologies, as I should have said ram air to create boost, as boost is defined as 14.7psi + xx.