[wheel1856]

not to sound like a smartass, but, one that fits and filters air should do it. How anal you are about high volume of flow or how small a micron it will filter is up to you. I have a cheap ass APC filter on mine because it matches the blue accents in the bay and it was cheap. filters air, and I haven't noticed any real difference between it and the original. I drive a BUTTLOAD and don't notice a change in gas mileage.

APC - cheap, does the job, will need replaced when the metal fencing around the filter rusts.

K&N - pricey, lasts a very long time, good rep, and is washable (quite the bonus) but what do you do while you wait for the filter to dry? (About 2 hours with the right conditions - don't use a hair dryer because shrinking is bad)

Fram - not so much. not designed to fit on a CAI

Bubba brand (generic) - about the same as the APC, but cheaper.