Here is my understanding regarding free flow filters.
Unlike older carburated engines, the fuel ratio in a computerised injection system is controlled by the computer, not the vacuum. Engine power is controlled largely by restricting the air flow. Reducing the the airflow with a restrictive filter will reduce the maximum power, and if it is significant enough cause the secondary Vtec cam to be engaged earlier.
The OEM filter is essentially oversized, so unless you live on a gravel road or drive in otherwise particulate filled air, the standard filter should work as well as a high flow filter. At least one member who tried a K&N filter found no difference. Another expressed concern that small particles of silica would get through the high flow filter and increase engine wear.
Blow by from the engine, routed by the hose to the air cleaner, is burned by the engine, reducing pollution and adding a tiny amount of power. Win, win.