Yea? He's on the road its not as big a deal depending on area.. go find a 4 wheeler with a K&N without a pre-filter (which they don't make). You'll find mud all down his intake. Dirt packed into the throttle body.
That means, not filtering, which means cylinder wear. Which means pre-mature blow-by and oil consumption. I mean, they offer no measurable gains, but do offer measurable filtration loss. I had just never thought about it before. I'm staying away from now on.
Well I didn't think about it, and I saw my neighbors throttle body. I do not have a problem with the oiled foam like you find on many motorcycles and lawnmowers, and a k&n with a good pre-filter would probably be good enough for me but at that point... why?