I am not a physicist, so you must take this with a grain or two of salt: my take on this is - consider it in terms of airflow - in CFM.

If your carburetor is capable of WOT airflow of 600CFM, this device must exceed that by a rather large margin to be very effective. If it won't, then at best it is just a non-functioning piece of ductwork, but more likely, it becomes a restriction to the passage of air into the intake system. Most fans of the size this seems to be will flow about 150 to 300CFM of air.