That's rght, air speed and fuel/air mix is more important than flow.
Think about a blowdart...Would you rather use a skinny tube, or a 3 inch exhaust tube?
Say your 1200cc engine has these figures.
6L/100kms = 6000ml/100000m = 6ml /100m @ 2800rpm (Highway revs in 4th ~100kmh)
Stoichiometric Fuel/air = 14.7:1 Air / fuel.
So those 6mls of petrol are being used to travel 100m (@100kmh) in 1/1000 hour = 3.6seconds. So 6mls of petrol + 88.2mls of air need to pass through the hole in 3.6 seconds. I expect I could blow more than 100mls of any ratio of liquid air through that hole in 3.6 seconds.. Of course, turbulence and different pressures will exist under different loads, causing additional flow restrictions, which might be overcome by slight changes in diameter (making much larger cross sectional area increases)
And keeping the speed of the flow up keeps the petrol air mixture consistant. So you want the smallest diameter/shortest path from the point of fuel/air mix to the cylinder, that can flow the required amount of fuel/air (@ given vaccuum/pressure) for the given capacity/revs.
In case any of this is totally wrong, buy 2 of these plates, machine out one of them to be a single hole, and run the car with both on a dyno...compare the results and let us know. I think you'll find the 2 holes are there for a reason.

Chris
