cotoy i'm runnin a 4.3 with the aa alum. radiator and a 3200 cfm flexlite fan with the varible speed controller and haven't had any overheating problems. I ran kelly flats 2 weeks ago it was in the upper 80's with alot of waiting for people and it never went above 205. The cooling system wasn't cheap but in my opinion it'll cost more in the long run ...