I also fly at hot and high elevation, usually round 30 deg C at 5800'
3.75" otlet brings me back to the original 95mm outlet I first had, I will try get an acurate fish scale to compare the tubes.

I think that the more "power" I felt on the outle side was due to the higher air speed, not thrust.

Wish I had the $ for a nice EDF or even Turbine but allas it is not in the cards, will have to make this setup work as best I can, more tinkering needed I think.

Thanx for all the input sofar.

Theuns