Simon K. suggested that I modify the height of the baffle in the heater shroud which blocks the incoming air from talking a shortcut to the exit point. ( less time in the muffler shroud, therefore cooler air for cabin heat. ) Simon modified his shround and it increased his heater efficiency by 30-40%. I alodined the shround and components, tomorrow I will rivet it all together. I will leave the inlet tube off at the moment, which will make cutting it's hole in the cowling much easier.