actually, i guess that's not much of a reply...
I my understanding of filters and such, what that K&N is doing is increasing the availible surface area and volume of air that can be filtered and "sucked in". The K&N, if set up right, can be configured to act like a velocity stack which (simply stated) actually keeps on a suckin' in air . That's why, when you turn your car off, you still hear a "fffffvvvvvvpphhh" a second or two after you turn your engine off with a premade HKS/GReddy type velocity stack . Air is still moving in. What really sucks in dirt is actually the HKS/RS Akimoto foam intakes that, after a few years (about 5 here in California) of engine bay heat and grime and washing cycles, start deteriorating and disintergrating. Not to fear, K&N filters from K&N actually have a million mile warranty which is a good thing. Neat trick = get a stock type K&N filter (if they make one...i've been noticing that they haven't lately made later-model stock inserts), cut your stock airbox apart (the bottom off..don't cut any sensors - doh!) and run to Home Depot. Go into the air conditioning/aluminum ducting section and buy some 6" flexible aluminum ducting and funnels. Get some BIGASS zip-ties, make a bracket or two (while your at Home Depot get a .49 cent premade one), run to the desired location and viola. (you want to visual all this first before you start cuttin. Make sure everything will be flush and TiGhT). You won't necessarily have the velocity stack effect but you will have cold air induction (maybe RAM AIR if you did it right) for about the cost of a K&N filter, some time and a couple bucks for parts. Neato....and you did it yourself..(i haven't checked the physical possibility of this yet, so if this is physically impossible, forgive) have fun...keep them gears a turnin'