autoguns,

sent you a pm. But in short, the 13x4W may be too small. Engine has to remain below 12K rpm to perform best.

We typically run 14x4W or 14x6 props. The Zinger pro 14x4 works well too.

Mine turns the 14x4W and ProZ 14x4 at 11K rpm with the turbojett muffler, and just over 10k rpm with the lite-muffler.
It loads down nicely with the 14x6.

They run a lot like control line stunt engines

I'm not sure how the ground clearance works out on the Twist. But I manage to get the Pizzaz off the ground with the 14x4.

Bob