Don't have one but have a UNI. I do however have an opinion i think has some validity. The stock filter's "screen", or the metal surround obviously inhibits the amount of air that can get to the element itself. So no matter how well the paper element itself can flow air, the metal screen inhibits it by only allowing a certain amount of air to get to the element. Look at it and you'll notice it probably only leaves 50% of the area covering the element open. Something i've yet to see mentioned but is obviously a big consideration. The UNI has a screen that is like a chain link fence and probably leaves a good 75% of the area open to airflow if not more. The K&n from what i can tell from the pics has no screen at all which i believe would allow more flow than either. However, from what i've gathered about the K%N it also allows larger prticles to pass. Therefore i bought the UNI figuring that from what i've read it's element traps smaller particles than the K%N and the screen covers a pretty small area that is probably negligable as far as air flow.
the point is that no matter how good a filter's ability to flow air is, the screen can inhibit it no matter how good it is. In my mind the UNI traps smaller particles but allows air flow good access to the element due to the screen. the K%N allows more due to no screen but also supposedly allows larger particles that from what i've read seems to be detremental.
2 things to consaider from what i've said.....
1)- the particle size thats allowed thru the various filters as i've stated is not fact, but just the general consensus i've gotten by reading a lot on the subject. I may be wrong
2)-the screens.....this is fact. the Uni is much more open than stock, and the K&N is more open than both, assuming that there is no screen, which i get from looking at the pics on brent's site. But it could be a fine mesh that the pic doesn't reveal so i'm not 100% sure.
In any case, i felt the UNI was the best compromise between an open screen and filter element ability to trap small particulates. but again the element's ability to do that is just my feeling from all i've read. But i feel good about my UNi. It did give me a boost and allowed me to jet richer and get even more power. If the K%N gives a bit more i don't care because i feel i'm safer with the UNI.
