You stated the pipe is connected directly to the shroud. Still the distance from engine to pipe is very critical. <span style="font-size: medium">The engine may have to be moved forward in the shroud to get the correct distance.</span> If the enging is close to the pipe opening, move it forward. Jet Central requires 1 1/2 inch from the end of the pipe. More power and cooling at this distance. My hand held infrared detects a cooling of the fuse once the engine starts. Note the separation of the engine conefrom the pipe in the photo. I can actually place my hand on the pipe at full throttle without any harm. Good luck on this problem.