Apparently, ... the T-1's CG allowance is fairly wide. I have the back of my tank about 2.5" in front of the K160's starter motor. It flies very well whether it is full or nearly empty on fuel. Due to a full-scale plane coming into the airspace right after I took off, I just landed the T-1 last week with both the fuel and smoke tank full of fuel. All the extra weight did not make a bit of difference. When flying inverted, it does not seem to make a bit of difference whether the tanks are full or nearly empty. So, apparently it does not seem to matter whether the tank is set back close to the turbine or forward a couple inches.