With these CAF, especially the pic by Inferno, surely these will collect crud, grit, leaves, water/rain, insects or a small bird etc and therefore clog up the filters very quickly. A lot of these after market cloth and foam filters do not filter as effectively as standard paper/fibre filters and therefore more chance for the engine to be damaged. At least with the standard setup, the CAF is behind the bumper and protected from these bits and still be drawing the same cold air. If its for RAM air effect, I would still say any effect is nil.
This is of course IMO.