Its a mod people do to try and get power gains that in my opinion is pretty much a waste of time.
It wont increase air flow. Will just change how the air actually flows. The engine will only be able to suck as much air as the filter allows.
You would be far better off getting a filter kit and fitting that. Even that will only gain you a tiny bit of a gain.
In simple terms if you want more power you need to put more air into the engine - the more air you put in the more fuel you can put in = more power.
