Ha, funny! I was just reading the same thing on thedieselstop.com. Couldn't be the same guy? lol
Seriously though, I personally think the K&N is not good for use on the diesel. I figure the suction that the turbo produces, will suck the oil right off the filter and let dirt pass thru. Just my thought!
What year is yours? 7.3 or 6.0? If it's the 6.0, most will say keep the factory one in. It's good till 500 HP and will filter better than anything out there. I did many mods on my 6.0 but I did keep the stock filter for that reason. With my older 7.3, I went with a Tymar air filter kit as the stock one there was too restrictive.
The Hauler - '05 F-350 4x4 CC Dually 6.0 Powerstroke
The Project - '90 Ford Bronco 4x4
The wife's - '11 Ford Escape
For every minute you are away from work...you can add two minutes to your life!