I have some friends who are K&N 'true believers'. Their loyalty seems to be based more on faith than on facts. When confronted with data showing how poorly their filters work, they usually blame it on 'rigged tests' and 'greedy manufacturers'. I've wondered what drives their zealotry, and found a quiz that might offer some clues.

Air Filter Quiz

Question #1 - Which filter pictured below has more pleats?
A. The filter on the left (Honda).
B. The filter on the right (K&N).
C. The lighting distorts the pleats. The photos should be taken in the air box, where it's dark.



Question #2 - Which filter has the most surface area?
A. The filter with 48% more pleats.
B. The filter with fewer pleats.
C. It's a trick question. The surface area is constantly changing due to temperature, humidity, and road conditions.

Question #3 - How is it possible for a filter with less surface area to flow more air?
A. It has larger holes (pores) in the filter media.
B. The filter is removed from the air box.
C. A special oil lubricates the air so it flows faster.

Question #4 - How do larger holes (pores) affect filtration?
A. Larger holes allow more dust and dirt to enter the engine.
B. Dust and dirt won't hurt anything as long as there's plenty of air.
C. What's filtration?