It would be interesting to monitor the pressure drop across various types and sizes of filter media- - - -metal mesh VS pleated paper, etc. About the only one I wouldn't waste my time testing would be the K&N that uses an oiled mesh media. One of them got so clogged on my Harley shortly after I bought it that the engine fuel-fouled spark plugs repeatedly. I switched to a 6" X 3" pleated paper filter, and almost doubleed the fuel mileage. I've been running the same set of spark plugs for three years. On the dirt track race engines, we would stack two 15" X 4" paper filters with a couple of layers of masking tape reinforcing the middle joint to be sure the 375 cubic inch (destroked 400) small block Chevy engine got enough air to turn 7K+ RPM.
It would be pretty simple to rig a water manometer to check on the pressure drop across various types and sizes of air filters, and "test- - - -not guess!"
Jerry
