We put a TT .91 FS on ours and test flew it last weekend. I ran it really rich for 2 tanks on the ground. The third tank, I began to lean it out a little every 2-3 minutes, and a long as it would hold the RPM, I let it run. Fourth tank was in the air. Had a dead-stick, but it was due to running the tank out.

The TT .91 is a great engine for this plane. Balanced perfectly with everything set up exactly as per plans.