I have some good info for you:
I have placed 6 temp sensors:
4 are on the bottom side of the tops of the cylinders, where the shadow of the air flow would be:
temp range is from 180 to 250 F, front and real cylinders have same temps. I am using that shroud I built. Ambient temp is 95 F.
Ok, one temp sensor (#5) is on the header, this reads 120 degrees F
the last sensor (#6) is in between the headers, near to the servo and the carbs, the temps are in 100 to 104 F range.
What do you think about the air flow in my cowl with those temps?