ok these bikes are designed from stock to only flow a given amount. they dont have ram air and use vacuum operated fuel delivery set up. what has been proven about kn is that once the air starts flowing fast there is too much velocity in the needle chambers and the fuel does not atomize properly mind you its a very slight power loss but why pay 70$ to make your bike slower? it also becomes much more noticeable with bike performance mods like full exhaust ign advancer etc.

 

If you want a K&N ill sell you mine for cheap. Under 5 miles on it. It made my bike sluggish and it does better with my stock filter in. I dunno what the PO did to it but my bike hates K&N.

 

So you get a K+N filter and drive up and down a dusty dirt road two or three times. Viola it's as good as stock!

 

i actually live down a dirt road as far as filtering ability kn is good.........as long as you keep them oiled.......

 

informative:
http://duramax-diesel.com/spicer/index.htm

Also, my own offroad oil-the-intake-boot-and-check-for-dust tests have proven to me that K&N's actually don't filter anything at all. I actually rebuilt a motor immediately when I found out it had a K&N on it for many years. I consider myself an intelligent person, and have had nothing but bad 'luck.' I've seen mild overoiling end the lives of countless mass airflow sensors, and I cleaned a hellish sludge out of my F2 airbox. Phooey to that junk.