[unclebilly]

I've run K&N's on several of my vehicles, past and present, not my Porsche.

K&N's do let some dust through, that's a fact. Are the dust particles big enough to cause any damage? I don't know.

I run K&N's on my Honda Transalp because a one shot $35 filter is cheaper than $25 for a new one every spring. The same deal with the Dodge Cummins Diesel 4X4 I used as a daily driver and won tractor pull competitions with, the $70 K&N filter was cheaper than 3 stock filters. My 4runner is a similar deal. I was also hoping for big increases in fuel mileage that I never got. In my little Chevy 1/2 ton, I'd never run a K&N - $40 for the K&N vs. $2.75 for a stock filter would take alot of filters to pay it off.

Everytime I've installed a K&N, I've seen a big performance increse, I think this is more to do with the fact that I'm replacing a dirty filter element with a new one than the improved breathing of the K&N.

What :P posted about the grease trick is something everyone with a K&N should try - you'll be surprised. I'm not sure if the dust particles are big enough to cause damage or not.

When I've seen dust on the clean side of my K&N's, I've chalked it up to the dust particles passing through the filter and picking up oil residue and plating out in the air horn because of the low pressure on the engine side of the element and never really worried about it much.