I agree. Toss that shroud, put a stock one on. Are you using a clutch ?The shroud is way too deep. Try it without it.
I thought that the shroud was irrelevant after about 25 mph of road speed.
So, 45 degrees differential. I measure 43 degrees differential consistently on mine. I also have a ECP radiator. Very interesting that you measured so high before. I wonder if you had a blockage that slowed the flow?185 inlet 140 outlet on the temperature.
I'm going to drive the 64 some tomorrow
And confirm the cooling.