No need to take pleats into account. I should have made it more clear that the 6 cfm rate was for the K&N type of construction with wire mesh supported pleated gauze, lightly oiled.
Air flow, practically speaking, or from the filters' point of view if your prefer, looks pretty constant. Even at idle there is a cylinder pulling in air 1000 times a minute or every .06 seconds. At 5000 rpm that's every .012 seconds.
