As always its important to ask what type of filter is being tested and what is the implied usage of such. I assume that they tested the standard airbox type filter vs. a cold-air induction type filter (tube and cone configuration).
It does make sense that the K&N would both fail first and have one of the highest dust pass-through rates.
K&N filters are designed for high-flow applications. Most people I know running K&N (cold-air) are track guys and x-crossers that remove and clean the filter after each use, some even break down their engine after each race.
The other thing to remember is AC Delco is the GM house brand. So, of course it would perform best when placed into the vehicle it was designed for. Just like the BMW oil filter functions better than a puralator or wal-mart brand filter.
Racing filters are for racing applications and require more maintenance. K&N will also respond and say that most OEM standards for trapping of particles is 96% (which it meets)
Anyway, those are my thoughts, cool test.
-ashley
Originally Posted by Guelphguy