I'm running an Evo .36 in my overweight (49 oz.) Caprice. Our flying field is approximately 6,000 feet elevation (near Golden, CO). I had the same initial problems others have reported but am now extremely pleased with the performance. The single biggest improvement was to go to R/C fuel. I'm running Patriot fuel which is 18% all synthetic (Klotz) and 15% nitro. Here are the physical changes to the engine: .272" diameter delrin venturi with case drilled for Super Tigre N.V.A., squish band narrowed .050". APC 11 1/2" x 4" prop cut down to 10 1/2" x 4" with tips shaped to original outline and taper. Launch 10,600 RPM. The engine runs in a rich 2 stroke and breaks smoothly back and fourth to a leaner two stoke. It runs very consistently and is very easy to needle. The engine seems to like to run at a higher RPM and turn a smaller diameter prop than my Magnum .36 or modified Thunder Tiger .36. Also, when trying to switch from the R/C fuel to 10/22, the run went completely to h__l. Switching back to the R/C fuel instantly "fixed" the run.
I don't like all those goofy cooling fins on the head or case. After running the engine with those on for a while, I finally machined them off. In my opinion, the engine looks a lot nicer, weighs less, and has not had any issues with overheating.
It's a very good engine. I now own two of them and may look for another one.
Chris