Help me out people. Those of you that have the Mugen or Spoon thermostats. When these are installed do you need to drain the radiator, like I would assume???

 

Yes.

 

Unfortunately, as cdelena points out, yes. The thermostat is on the lower radiator hose, making the draining of the radiator a necessary evil. Why Honda didn't put the thermostat on the upper hose is beyond me...that would have made the swapping of it much easier.