Doing some calculations, it seems as though the Spoon snorkel at speed should be effective in channeling air beneficially, given no pinch point.

Consider that I was going at least 115 mph at Buttonwillow on the back straight, and that the snorkel opening is 7.25" by 3.25". That might translate to 1844.8 cubic feet of air scooped up per minute. This is near my 5th gear mark with 4.77s, just before shifting occasionally to 6th. Given the decreased opening area of the end going into the airbox, how much less cfm might be expected...?

For a 2 liter engine turning 9000 rpm, consider it using 635.7 cf/m of air, taken in the most simplistic sense of no precharge air compression, etc. This might suggest, at speed, the snorkel is beneficial, even with somewhat of a decrease in volume delivered due to airbox end size. Given lower speeds, with a pinch point, the snorkel may be a hindrance. Maybe even at 75 mph or....?

I think the stock S2000 is also able to channel air into stock snorkel, given the higher speed pulling power a notable tuner told me he noticed compared to other comparably powered cars. I think he said a certain amount of air induction was helping.

I welcome any miscalculations pointed out to me, as it has been awhile for me and algebra/math, etc.

I have a Mugen hood and have reconfingured my Spoon snorkel to get rid of the pinch point over the radiator.

 

I would point out one oversight... that the engine being a 4-stroke will only ingest air into the cylinder every other revolution. (One combustion downstroke, and one air/fuel intake downstroke).

That being the case, you would see the 2 liter engine at 9000 rpm ingest only about 318 cf per min (1/2 your original figure).