I have the FIPK.
You'll get very mixed responses on this one. Do a search, and you'll see what I mean!
For what it is worth, I own the FIPK. It is on my car now. I like it, but I do have 2 complaints. It seems to collect a lot of bugs (probably because I nighttime drive a lot), and I don't really like that it is black and made of tough plastic. Granted, the whole 'plastic' thing is supposed to be one of the reasons it makes more power because it keeps the air cooler than an aluminum pipe that supposedly heats up and therefore heats the air.
Frankly, if I had it to do all over again, I would get the C&L Trufit intake pipe instead. You will get the same performance, I am willing to bet. And you can use whatever filter you want. I would buy a K&N Filter for your stock filter housing, and buy the C&L Trufit. The Truefit and the Stock housing peice together, therefore allowing you to put whatever filter in your car that you want (assuming it'll fit the stock car).
But, if you want, I will sell you mine, and I'll do what I just suggested to you. ;-) I DID feel a difference in throttle response, and the car does have more power, and you can definitely hear the air being sucked right in just like it is supposed to. As far as pure functionality is concerned, the FIPK works great. I wouldn't be unhappy with keeping mine on my car for the rest of the time I own it. It does the job it says. But, I just like the metal look better.

I already have a regular K&N stock filter too, so I'm kinda wasting it since I can't use it. It doesn't fit the FIPK Cold air intake. Weird, huh?
Man. I gotta cut down on these post lengths!