I don't see have the flex is going to make much of a difference. The fan's impact is at low or no speed where the flex and non-flex should be equal. And both fans are designed to zero themselves out at highways speeds where yours is getting hot again.
Looking at your temps vs speed info, I'm thinking you just don't have enough water flow. Is the WP pulley the correct size? Does the Flow Kooler water pump come with the cast impeller vs the stamped design that many have found to make a big difference when looking at replacement water pumps?
The distilled water/water wetter issue is unclear as to whether you put in any coolant/antifreeze. I run 50/50 distilled water/Prestone. I mix it myself vs the pre-mixed versions.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
