I havent tried one of this yet, but I am getting awesome performance from my Enya engines using 3 blade low pitch props for piped engines.
The Enya SS50 is working with a 3 blade 12.5x3,75 and the 61CX with 3 blade 13x3.75. Both can be setup to run 4-2-4 or 2-2-2 and if you put in a light model I donīt see why it would not work 4-4-4.
The 3 blade 12x3.75 did not load the SS50 enough, it went like a bullet and it needed the 12.5x3.75 one. The Enya 61CX is the friendliest most powerful engine I have ever seen for C/L, it works with any prop any venturi size and it will carry huge and heavy models.
The Enyas are not stunt detuned, they are similar to Magnum 36. So my guess is that you could get killer performance out of the Enya 40XZ using a 11.5~12x3.75 3blade prop.
The Enyas come with a small venturi, to get more power I recomend using a larger venturi. I use a 8.0mm with Enya SS50 and 8.5mm with the Enya 61CX.
I bet the 40XZ will work mighty well with a 7.5mm venturi
Martin