a good thing to test your air filters is to apply a light coat of oil in your intake tract.
go riding, come back, check out your intake tract.
is there obvious dust?
or is it clean?
personally, i do not like k&n because they did not do well on this test, the filter was clean and oiled.
uni did not do good either.
i was happiest with notoil, twin air, and the oem filter on my bike.