I have one of the first examples of the Evo 15cc and fly the snot out of it. One of the frustrations people ran into, was that the fuel line provided with the engines was not much better than Tygon for the pressure tap line, and Tygon is unusable on the muffler, due to the heat. Simple solution, just use good old silicone fuel line on the vent line to the muffler, holds up just fine, you just can't use it on the carburetor line which is constantly filled with gas.
Pete