Not to offend but I highly doubt that there is a real ram air effect, more likely what you are experiencing is a less restrictive intake since there is now more area to pipe in the air and cooler temps allowing for more power.
To start the calculation using my car a 3.8l V6 @ 2000rpm consumes about 67CFM assuming 50% VE. For a straight Flexable 3inch pipe to flow 67CFM the velocity of the air in the pipe would need to be 1364.91fpm (
Air Duct Calculator - EfficientComfort.net) or the speed of the air needs to be 930.62mph. Even if the speed of air is 11 times faster than the speed of the car I would need to be moving 84.5MPH.
<s>Your truck</s> The 2.2l car in the first post at 2000rpm 50% VE uses 39CFM with the velocity needing to be 794.5 fpm or moving at 541.7MPH going by the 11 again (highly doubt the air would be moving that much faster than the car) the speed needed is 49.25MPH.
One thing that is not included in my calculations is the extra restriction produced from bends in the pipe see
ZZ Performance