without getting to scientific, an unboxed CAI should still suck in cold air if positioned correctly. You have the force of the air coming in through the grill at colder temp (and lower density) so should create an interfacial barrier i.e. hot air unable to move to the front to be sucked back in. If an unboxed air intake was installed incorrectly and too far back into the engine bay, then I could say with 100% confidence that it wouldn't work and would suck in hot air.
Another problem, the K&N does replace the high beam light, from what I can tell, which will probably cause a defect problem here in Australia.