Two concerns I have about the inline thermostats is;

- Restricting flow and increased pressure. They are certainly used in other Rotax applications so perhaps not an issue though some models use a by-pass.
- Restricting flow to the cabin heater as I think the heater T is down stream from the likely location of the thermostat. This might keep the coolant temps up but not provide more cabin heat.

For these reasons I went with AL tape on half the radiator, seems to work OK but I liked the idea of the coolant thermostat better. I use a thermostat on the oil and it works great. If others know why my concerns above are silly please chime in