Of those of you who have used flex fans and had good luck, what brand(s)did you run? It appears that the most prominent fans are Flex-a-lite. Summit also carries Derale. I read on another post that the style or taper of the blades will make a difference in how the fan functions and the amount of air it will move. It was suggested that one look for a heavy duty flex fan. I don't know if that is opposed to one designed for racing applications or what.