The cg for version 3 is 3/8 inch in front of the rear cabane wire supporting the top wing. There is no recommendeded engine offset for either 2 or 4 cycle engines, however they mention the use of Ernst plugs for up to 2 degree right offset if that is your personal preference. They are to be installed behind the engine mount. I'm using a 12 oz round Pylon tank to lay in the bulkhead craddle.