More good info on this other post: http://www.vehicross.info/forums/sho...=&postid=47731

Morgan says his filters down to 20 microns and it has fabric inside that stainless mesh. Properly oiled K&N or Green filter traps down to 5 microns. Bigger (more surface area) the filter the better... Green seemed to be built better than the K&N and I have been a long time K&N fan.