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Have measured mine, and above 45mph, it does not suck!

The term suck was used as part of the prior joke, the actual term is vacuum. The function is to increase the amount of vacuum and there by increase the amount of air forced into the compression chamber. The point of above a certain speed depends on whether are not you have what is called a waste gate on your turbo. But as stated the air filter and exhaust also have a part to play.

water, BARR, PSI, etc. "The function is to increase the amount of vacuum and there by increase the amount of air forced into the compression chamber"

The term you are looking for is "manifold pressure". On a gasoline engine it is used to measure power setting of the engine, normally aspirated or turbo. The higher the MP, the higher the power setting. It is always a positive reading, but will be below atmospheric pressure on non turbo engines.

There is no such thing as "vacuum". Pressure, either above or below ambiant or atmospheric, is all still pressure and is measured in units such as inches of mercury, inches of water, BARR, PSI, etc.

My intake manifold is never below ambiant air pressure, and is often anywhere from 2 to 4 PSI above atmospheric pressure, this is the pressure the intake valves see, and is downstream from the turbocharger. The wastegate is closed at any MP below 15 PSI above atmospheric.

On the inlet side of the turbocharger, at speeds above 45mph, the front air scoop coupled with the ducting and large, free flowing air filter, produce at or slightly above atmospheric pressure. I have measured this area to get the ducting correct. The intake manifold has a pressure gauge on it at all times.