I was thinking of putting K&N's on a 400EX and 300EX. Is the housing you slip the filter onto strong enough to support the filter? The reason I ask is I put a K&N on my Chevy truck, and the band that holds the filter in place, collapsed the stock housing. Actually it dimpled it and let in unfiltered air around the seal! It was on the bottom side, so I didn't see it until I went to change filters. I drive and ride in VERY dusty conditions, so I'm not sure how bad it really is, but there was some dust inside the housing!

Anyway, the 300 seems to have a pretty substantial housing, and I think it will hold up OK. The 400 housing seems much softer, so I am a little skeptical. Anyone had any experience with these?

Also, what do you think of the K&N in general? I ride desert XC and would always run an Outerwears prefilter. I'm not sure I trust the K&N completely in these conditions!

 

Also, is anyone using the K&N "Airforce" pre-filters. These are oiled open cell foam. They claim they stop 90% of dirt, with only a 2% restriction in airflow, where the Outerwears pre-filter has a 10% restriction. I ride in stuff that is more like talcum powder than dirt, so I want maximum protection, but of course I also want maximum preformance!

 

Everyone has their own opinion of the K&N filters. I have run one on my truck for years (just clean it-oil it and keep on goin). On the other hand, I would never run one on my atv. Research and see how many horror stories you find about the k&n filters on atv's and dirtbikes (and there are many...search in this forum). I rarely hear anything about a properly maintained, quality foam filter destroying a motor.

 

I've heard the horror stories too. My thought was that a pre-filter (especially the foam one) might provide a margin of safety???

 

I've been using K&N for so many years I can't remember, and never had a problem with them or destroyed an engine because of them. Had them on my old 4 strokes and run them on my Rs. Everyone in my group uses them and never a complaint from them either. I just change it after 6 hours of use. I ride dunes a lot, and some desert (Red Rock, Johnson Valley, Slash X, Hungry Valley, you oughta know these places). I've never had them let dirt through.
The air box on a 300 will support the K&N without any problem. I can't answer about the 400.
"That's just my opinion. I could be wrong."