Brian I am not running a thermostat as I figured I would be running into heating issues. I think the biggest thing is by dropping the lip and giving more exit air, its really doing its job. The heat exchanger was to help bring down the oil temps as I figured they would be running hot. It should also bring up the oil temps when the water temp is higher than the oil. With CHT at 180 and oil at 130 the heat ex-changer is heating the oil and cooling the chts. I will have to try and fly it when OATS are a little warmer and get some better numbers. I was building as fast as I could to try and get it up flying in the heat.......oh well. I may need to look into running a thermostat. Why did you run the thermostat that you did? Do you happen to have a part number for it?