Originally Posted by SkyPilot
K&N makes a stock replacement filter, the only way they would know you have it would be to take the cover off the box. It might be a happy medium in your situation.
Or try another dealer for warranty work. My Service Mgr loves my focus and the things ive done so far.
Technically that's still an oiled filter, so if/ when they open the filter housing during an oil change that could still bring up trouble for them if their dealer is going to be a jerk about it, in full violation of the Magnuson–Moss Warranty Act which states that the warranty can't be invalidated unless the change can be proved to have caused the problem essentially.