The flat panel aftermarket air filters are just as good as the pods. As long as the air flow is there its all good. Obviously the colder the air the better. The reason you get added performance when changing to a pod rather than keeping the factory box is due to the fact that the factory boxes are very restrictive (for noise amongst other reasons). Pods instantly have more air flow and can breathe easier.

If people try to tell you that if the pod is just sucking air from in the engine bay its not good for performance then i wouldn't be asking them for any sort of mechanical advice... :roll:

Upgrading to a pod (or any aftermarket filter) will definitely give some small power gains, more noticable in non-VTEC engines. That is with the pod in the engine bay, without any piping bringing cold air from the front of the car. With VTEC engines, the power gain sometimes isn't much at all (1-2hp) but you get the induction noise (which we all like)... :P