For the same reason an M1A1 Abrams Main Battle tank doesn't have 4ft thick ceramic/steel/Kevlar armor... COMPROMISE.

The AH-64 needs volumes of air for the turbines. A paper element would have to be huge, COMPROMISING aerodynamics and radar signature. It is easier, especially when you have a full-time maintenance crew paid by the government, to use a simple filter and re-build every XXX hours. I do seem to recall the original AH-64 was choking to death on desert sand... and they didn't fly due to dust. Hmmmm....

You still haven't addressed my statement:

Two identical 144 sq/in filters:

A paper element filters more particulates and flows less air.

A foam/oil filter flows more air, but allows more particulates into the engine.

Which protects the engine better?

My opinion to the original question... at each oil change - it is cheap insurance.

As for the debate with K&N and paper, I have used both in my Porsche and would not ever recommend the K&N filter. Yes, it does allow more airflow but at the sacrifice of filtering efficiency. My K&N went into the trash and I would never consider installing another. Again, this is my opinion upon what I witnessed with my car - which is rather concrete in my eyes.

To risk adding fuel to the fire, my car came with a K&N from PO. With regard to cost I don't know that the K&N is cheaper at all when you factor in initial cost PLUS cost of recharge kits and the time it takes to clean and recharge them. I think after this next recharge I may go back to stock element just because it's so much easier to change. They do have a good reputation, but I'm not sure if this is due more to performance or protection. They certainly seem to have the performance enthusiasts sold.

the arguement between the 2 types can go forever. but bottom line when we tore the 1600 engine apart...........not one bit of wear assoc. with particulate ingestion. we are talking 7 races where basically we put an 8x8x16 block of concrete on gas pedal and went like hell. remember its a 1600 eng. so it wasnt like we were in front EVER! so talk about sucking dust..................FOR MILES! if we had used just a bandana over face,instead of parker pumper w/k&n we would have died from dust ingestion.no dust ever found in throat of solex either. i have k&n's on every vehicle quad bike i own. unreal customer support, unreal on site race support(at least baja venues). im 48 yrs old and have been doing the dirt thing foreever. have used paper and foam. both have clogged, or fallen apart. yes k&n's are a pain to clean...........but w/p-car how much dirt is it seeing unless your running paris to dakar? i have about 500 yds of dirt road i have to drive off of main road to driveway(very slowly), but due to winds etc. storms construction this place is one giant dust bowl. since i went with fabspeed airbox and k&n i took g/friends nylons and wrapped over airbox. cheap works great, mimimal restriction. when racing our car or pitting others no matter what engine or class, pit procedure was to pull k&n socks off of filters and replace with new. never touched replaced cleaned filters EVER in god knows how many races, while actually racing. after race of course we cleaned them. socks come in foam or nylon and use both on everything i own. socks are simple to wash and keep filter clean. i just throw nylons away at first hint of dust and replace w/another pair on my p-car.

as far as your specs paper vs. foam. k&n is not a foam filter. but really look at what your trying to achieve here. more hp and no particulate ingestion sanding your motor. i have literally run race vehicles into 4ft deep silt beds. in 1982 we ran my mitsuibishi pre-runner the week before the mint 400, up to the door mirrors in a silt bed! boy did we miss that course arrow big time! behind me was a rental stock chevy blaser that finally just stopped cold due to paper element flat clogged w/flour silt. after everything settled down and we towed blaser out we cleaned airfilter and got on different course track. blaser ran fine after cleaning filter and i never touched mine til i got back to phx from vegas. that was what sold me aside from numerous other experiences. hard to swallow but k&n's work better when dirty. you nor any of us will EVER take our p-cars thru that kind of abuse. like i mentioned before using the socks allows you to stretch the maint intervals quite abit. if you have stock airbox just get some panty hose and zipty around air inlet nozzle and that in itself will help a paper element or a k&n. im the last one who wants to spend money or have to invest time in a rebuild of any motor. when you have 1 vehicle its not so bad, but when you have multiple vehicles it becomes a big deal and real spendy keeping up w/maint.

what we have found over years is some people dont read instructions for K&N's and really screw themselves. dont ever used compressed air to clean out pleats EVER! you will blow holes thru them and you are screwed. just gently tap dirt/debris off, place in pan w/cleaner soak, use toothbrush to clean pleats, and use gentle water from tap spraying from inside outwards. let dry and re-oil each pleat ONCE! let dry and come back and respray any pleats that didnt get enough oil. wipe edges of filter off w/ rag and install. go like hell!

now for the top tip of the day! use 409 spray cleaner instead of k&n cleaner. cheaper and does the same thing as k&n cleaner. i dont work for them, i just have been up to my ass in silt and have been amazed the vehicle still RUNS!

When I bought my car, the service records indicated the air filter had been changed 2500 miles prior. I pulled it out, inspected it and it didn't look very dirty at all, so I thought I'd save the new filter and 'use up' the old one. When the weather warmed up and I took my car out of storage, I decided to put the new one in anyway. The difference was unbelievable! Sounded better, pulled harder, idled smoother. I got the Mahle for about 15 bucks at a local shop - money well spent. Swap the old for new and see for yourself.

I bought a new one. SmileWavy