Thanks for the great responces to my questions. The Greatplanes Extra 300 40 size arf requires a .40 to .51 2 stroke. I origionally had a MDS .58 which weighed 20.45 oz. I was extremly displeased with this motor and only flew once with it and had a dead stick landing. The saito 100 weighed 20.5 oz, Hopefully it will fly well with this motor my pockets are empty after the Sato 100 purchase and it would be hard to dish out $$ for a new motor at this time, I plan to practice with the GP extra, but purchase a 120 size aerobat for my first IMAC fly.

I have a couple of more questions:

If you were on a budget and had to purchase a 120 size, ARF, preferbly with a 2 peace wing for IMAC flying which one would you purchase and what power source would you use?

Back to the gas tank thing. When you balence a 2 stroke empty then add fuel the CG shifts dramatacly forward. When you balence a gasses with the tank over the CG the CG remains the same. Is there different CG points depending on wether you will be installing a gasser or a 2 stroke?

Example you balence a 2 stroke type plane 4" behing the leading edge with an empty tank to mfg recomendations. You then add fuel and the CG shifts to 2" behing the leading edge. If you moved the tank over the CG with a pump where would the CG be at 2" or at 4"?

Thanks again for your help