fwiw, I used a automotive water line hose (6 inch) to extend the breather tube onto the exhaust pipe. the breather tube burns to contour against the pipe. coldest temperatures flown -27C at high altitude and -20C at low altitude. no other holes in vent piping. this is only a data point and I fully support an additional hole in the vent pipe if you feel the need.
upper vent piping silicone elbow is holding up well.
upper vent piping silicone elbow is holding up well.
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