I finally got my water temp gauge hooked up and I found the cooling system is dependant on air flow (pretty obvious I know).

cruising temp is 85 deg (on my gauge in top radiator hose just before thermostat).
stop start traffic or giving the car a good workout. 90deg
idling 95deg and climbing!

Mazda did a good job ducting the radiator and oil coolers so watch out for poorly ducted aftermarket bumpers as the coolant temps will rise.
for track days it might be best to stop the car and pop the bonnet.

 

Have you seen this???? It is a radiator cooling plate that helps direct air onto the radiator. Just how good it is, I don't know. Does the RX-8 need extra cooling???? I don't think so. Is the standard one sufficient??? Probably.

Anyway, these are available in aluminium and titanium for the RX-8. In Australia, apparently.....

 

that's just a reproduction of the plastic cover that is already in place. maybe it helps on cars without them but replacing the std plastic one with metal isn't going to do much.

from what I've read (in the odula intake threads on this forum) there is also a plastic duct underneath the VFAD ducting. this would direct much more air to the radiator. something to think about if you have to remove such a divider.