Im Flying mine with a 91 FX and 15/6 apcs. It is truley awesome. Not way overpowered, but just about perfect. I flew it for fun in an IMAC contest because I lost my Edge the day before to a radio glitch. The judges scored me and I took 1st place in Sportsman IMAC. The plane is just way fun with the 91. You can as I qoute

"take off point straight up climb about 50 feet, pull it over on to its back, angle it down then 1/2 roll to up right followed by a nice touch-n-go!"

if you really wanted to. Well any decent engine and you will have fun with it. I have all the coupling mixed out and you can knife edge from horizon to horizon. Hope this helps.