Mine has the ZDZ 80 single w/Bisson pitts muffler. Pull-pull on rudder using Hitec 5735 mounted about 3" behind the wing tube. All batteries (2- 6v and 1- 4.8v) mounted on top of the engine box (No RF problems). Still had to add 18 ozs of lead in nose of the cowl. Balances 3/4" behind the wing tube. All up weight is 23 1/2 lbs. Flies just fine with no bad habits due to c.g. location.