Kitfoxes have used an under the belly radiator and it has worked fine on the 582 since it came out. It also cools the 912 just fine. It probably does create more drag then the cheek radiators or the other radiators Avid used, but does cool better. Those radiators are available from Kitfox, and Murle Williams Aviation also. The 582 is a fine engine if you run it properly. But it makes 64 HP so it just wont have enough power on a 1400 or 1500 lb gross weight aircraft like the later model Kitfoxes. In an aircraft that weighs half that much it has lots of power. I've owned and flown 4 Avids and 2 Kitfoxes with 532, 582, Jabiru, and 912 engines. If you have a 550 - 600 or less empty weight aircraft, the 582 does very well. JImChuk