I wouldnt disagree in the base theory you desribe apart from 2 areas, unfortunately, they are fairly major..
1. the fig of 1psi that you use is fine for comparative purposes, but rarely as high as this. A modern induction system cuases mimimal restriction, but this can certainly be measured with a differential pressure gauge. the restriction is constant unless removed. An intercooler drop of say, 2psi on a turbo engine is not uncommon, in fact its pretty damn good lol, however, by increasing turbo boost the drop remains the same. It doesnt overcome the restriction, it just increases the pressure out in proportion to the pressure in with the same loss. So, to increase the pressure at the throttlebody end but NOT increase the pressure at the intake above atmospheric doent work effectively.
2. Air disturbance due to vehicle shape and drag. The is a layer of confused air close to the vehicle body which is aligned at an angle related to the shape of the vehicle. To get a vehicle to have good low drag figures, it needs to have a reasonably aerodynamic shape. If you draw a vehicle (say a 1.8 clio

) side on, then you can imagine the effect of coloured smoke being flowed over and around the front as in a wind tunnel. Where the airflow bends to flowup and over or is deflected in whichever way, it speeds up.. as it speeds up, the pressure drops (Gas Laws). What happens if you put an opening into this frontal area ?. well, it is surrounded by a deflection area where the actual pressure can be lower due to directional change (oooops). Also, a turbulent effect occurs at the opening in proportion to aerodynamic flow. What you have done is create an area of chaotic air movement. To add to this, the air flow through the opening (and induction system) is not constant, it is a series of low - highs that form standing waves in the induction system, this has the effect of air moving in rapidly, then stalling in effect, at the opening, the same occurs, this adds to the disruption and can actually cause a pressure drop. That is why the manufacturer places the air intake in an area of cool, but relatively undisturbed air.
Thanks for the genuinely well thought out post Simon, I would be interested in you and your bros comments.
ps, the progressive is looking promising..
Joe.
Joe.