I have not switched from the disposable (Fram etc.) style filter because I have yet to see any hard data that says the K&N, Amsoil, etc. filters do a better job of removing dirt from the incoming air. Sure, they may flow more air, but is the dirt-removal capability the same? Remember that increased airflow=increased hole size in the filter elelment=increased potential for dirt particles to pass through. Yeah, the race teams use them, but their desire is max airflow and not necessarily efficient filtration. Remember that they rebuild their engines all the time as a routine matter... We have a trade-off here in that we all want better performance and better mileage BUT we need max dirt removal capability because most of us don't rebuild our engines all the time. I use an oiled-foam element filter on my dirt bike but it gets cleaned and re-oiled after every couple hours of use.
Where does the figure come from that says that 40% of engine wear comes from dirt in the incoming combustion air?
Until I see the hard data and science behind any of this I'm not switching. Maybe some of you guys have the info? I'd love to see it!