There seems to be a debate about K&N filters vs. stock. Everyone seems to agree that K&N flows better. The question is filtration ability....so I did a little test. I drive between Santa Barbara and Bakersfield 2 times per week. It is a brutal gusty dirty air drive that is 300 miles round trip. I used a stock filter for 3,000 miles...then used a chemwipe to collect dust particles that made it thru the filter and were inside the airbox. I did the same with a K&N filter. Again it was for 3,000 miles. The chemwipe with the stock filter collected approx. 360 particles of very small size in 3000 miles. The K&N filter collected 267 particles of very small and small dimensions. A few of the K&N particles were slightly larger than anything I saw with the stock filter. (Very slightly) I used a dissecting microscope to collect the particle number.