4x4 ic very good peice of kit loads bigger than the 2wd one, which is too small for anything other than standard. It might be that a 4x4 ic is as good as a rs500 one. i think it was a feature in fast car years ago done by paul bailey, he tested a tuned saff with a 4x4 and a an rs500 cooler, there was nothing in it, the rs500 one presented a bigger surface area but the 4x4 is deeper, at the end of the day that extra slot on the rs500 bumper is there for a reason, to maximise airflow, the sapphire doesnt have loads of space for air to get in the front of the car.