So that link says the K&N filters 97% of the dirt.
If this pic below is 3% of the dirt after only 501 miles, I want to see what 97% of the dirt looks like on the tested filter.
Obviously this dirt occurred in the first portion of the 501 miles. Because as the 97% of the dirt accumulated on the K&N test filter, it progressively clogged it up letting progressively less air, and dirt, through to the test sample.
Heck, I don't know. It may all be legit. My concern is that the filter business is highly competitive. Bobistheoilguy is a site that has cultivated industry respect by presenting scientific, credentialed information. The fact that they'd present unscientific testing is puzzling to me. That would be like them posting one of my redneck tests! The fact that
www.bobistheoilguy.com is sponsored by a major distributor of wix filters, a line of filters competing with K&N, Baldwin and Amsoil, makes me a little suspicious. I figure if the sponors' filters didn't perform as well the article likely wouldn't have been linked.
But this is still what gets me- if that test filter was placed in the entry point of the tube from the airbox to the throttle body, which is what it looks like to me, and it is so absotutely efficient that it can catch all of the 1-3% of dirt passing the test filters, I can't see how the sucker could drive the car. That matierial would be so restrictive. Some of the other links you've given look legit but I've got too many issues with what's presented as AnthonyS's tests. Still, it simply confirms what we know already.