This report (see link) doesn't tell me anything that I did not already know. I've seen countless cars on the rolling road with K & N Filters fitted and the resulting power drop-offs.
Do yourselves a favour guys and steer clear of them unless, as I always say, you are doing the Paris - Dakar or crossing the Nul Arbor Plain in convoy!
Stick to an OEM filter or a non-oil impregnated type from BMC, Jetex, Pipercross or Ram Air.
ISO 5011 Duramax Air Filter Test Report