Here's an idea for getting the truth about the K&N filter.  If someone out
there has a little extra cash and sometime (I have time but not the cash
right now) a simple experiment could be run to see how well the K&N
actually filter.  Build a fixture to hold a K&N with a normal paper element
behind it.  Put a descent size blower on the setup to pull air through the
two filters.  Put the whole contraption somewhere dusty and let the thing
suck air for a few days.  If the K&N filters as well as a paper element
then the inner paper filter should be clean while the K&N is filled with
junk.  If not you should find stuff in the paper element.

Experiment two.  This is more scientific but would take more time.  Setup
two identical blowers that pull the same amount of air.  On one put the K&N
on the other a standard paper element.  Record a precise weight for each
before the experiment and then after a several days of sucking air remove
the filters and reweight.  The difference in weight of each filter will
tell you how much crude each has captured, whichever captured more is more
effective.

Could make an interesting science project for somebody's kid.

Dave K.