Suprised no one has asked yet.... Is this your first plane? Are you with a club?

The SS is a great flying plane, you'll love it. I had one, may it rest in pieces now though.
If your fuel is coming out the top tube and into the muffler even though your tank is emtpy, then you have a plumbing problem. Make sure the muffler line goes to the top of the tank inside. Your carb fuel line gets connected to the line in the tank with the clunk on it. Fuel should not come out the muffler line until the tank is full to the top.

Sean