http://www.mkiv.com/techarticles/filters_test/2/

 

its a good read, been around for a while.....

 

thats on filtration, where is the one about flow?

i want to say it was a BMW or Porsche guy or something, but i'm positive it was a euro guy who conducted the test. he would measure the height of a ping pong ball that floated on the air the filter let through, and then cover it with cardboard to get the same flow rate and calculate the percentage blocked with that?

i think that tells the true story, but i can't find it ANYWHERE

 

Good write up but it's from August 1999. A little outdated.