I have the C & L C.A.I. I dont ever 'change' mine. Once its dirty or dry, I remove it and wash it according to the suggestions by C & L and then let it dry. Once dry, I recharge it with the spray that re-oils it and lets it function as intended and reinstall it.
The idea it is wide open is what helps it deliver air better to our cars verses the 'box' one that originally comes with it, so along with the proper tune, can provide modest to good performance improvement.
As long as the filter is maintained correctly and cleaned when necessary, it is a HUGE upgrade from the standard air box that initially came with the car. As far as changing it goes, it can vary (as the side of the box notes) with frequency of driving as well as the type of roads you typically drive it on (think gravely, dusty roads which can obviously cause it to likely become dirty much sooner).
Last edited by Andretti1; 6/3/10 at 04:03 PM.