What are yall using for radiator fans?

I have a flex a lite fan and thermal clutch. Fan has a steel center section, aluminum blades. 6 blade, looks like an old stock unit minus 1 blade. Rated at 4000rpm, with the thermal clutch keeps it cool and should free up some horsepower over a fixed blade.

I have no real world experience with the flex blade fans although I have heard they use more hp to turn.