There are those, including myself, that do not agree with the anti-K&N BS that has been posted here. I have used K&N units on many different dirt bikes and off-road vehicles, and have never seen an incident where intake dirt caused any problems with cylinder wear. If the K&N unit is oiled properly, it will filter as well as anything out there. My current truck has had the K&N filter for 145K of the 165K on it. Its been used in a variety of very dusty environments and the last compression check I did (10K ago), was excellent.
I also follow a board for my 86 F-250 diesel truck. With the NA trucks, the easiest way to get added HP on these non-turbo trucks is to increase the air intake. There were some pretty cool intake mods, and many, many discussions on air filters and filtration. There were members who did regular oil analysis for their rigs. I saw pretty solid evidence that for the pre-powerstroke Ford diesels, the addition of the K&N filter dramatically increased the particulate count in the oil analysis, particularly silicates. This was on rigs that were religiously maintained (to the point of regular oil analysis). I would hate to think what Joe Blow that doesn't know how to clean and oil that filter is doing to his motor. It was enough to make me stop using the K&N.
I would be curious whether the K&N application for the Monty is any better. What kind of compression numbers are you getting? Wouldn't increased particulate levels in the oil also affect the main bearings? That kind of wear wouldn't show up in compression numbers, but would in oil analysis.
Anyway, something to think about.
