Is it possible that a brand new clean stock air filter is just as good as a brand new K&N? I have a 2004 3.01 Z4 with a brand new stock air filter from the dealer. But I bought a K&N performance filter because it has the word "Performance", right in the title. I guess I expected more "Performance" with it. I know its just the stock intake, but the z4 doesnt have a bad stock intake setup so I figured a K&N filter would improve on the design. But it doesnt seem any different to me. Is it just my imagination?