Adrian, you are correct in your assessment. I was using the equations from Maximum Boost and did not convert cfm to lbs air per minute, (Done correctly all calculations should be lbs air and then converted to cfm). The calculations are “back of the envelope” and are only meant to show the limitations of the Viggen Intercooler.
I use a volumetric efficiency (Ev) of 0.85
I liked the last point you made.