I think the thermostat on my E46 is starting to go bad as the coolant temp hovers around 85 degrees while running down the highway. I seem to recall that the thermostat shouldn't open until 88 or so. Does anyone happen to know for sure?

While I'm in there, I plan on replacing the water pump, radiator, and upper & lower rad hoses. Is it necessary to replace the radiator or can I get away with doing just the expansion tank?

Finally, can anyone convince me that I should upgrade to the EMP Stewart water pump? So far, I haven't had any cooling problems and as far as I can tell, the water pump on the E46 is a little more robust than on the E36.

The car is 6 years old and has 102k miles and sees roughly 6~10 track days per year.

Thanks,
Anand