ORIGINAL: Sport_Pilot
You forgot to deduct the muffler pressure lost in the outside loop. Because the muffler vent is at the top it is reduced by the head of the fuel.
I would like to agree with your statement, but I cannot.
The static pressure in the muffler is exerted over all the surfaces of the tank and the tubes, regardless the location of the fuel inside them.
That is the Pascal's law.
http://en.wikipedia.org/wiki/Pascal's_law