I learned something today (type 44 air filter change)

[John Larson]

Finally a voice of reason in a sea of advertizing urban legend victims.  It
is refreshing to hear the truth about K&Ns.  More frequent service with time
consuming cleaning and re oiling using their expensive concoctions,
resulting in less efficient cleaning of the intake air.  Sure they pass more
air per square inch, but have only a small percentage of the filter area of
the OE paper filter, and allow larger particles to pass.  John