A Fluidyne radiator will keep the engine cooler but does cost quite a bit.



There are no better thermostats than the factory mazda one. As mentioned above the rotary needs to stay around a certain temperature to run best.

 

Fluidyne is good but expensive. You can get a Koyo aluminum rad at Sportcarmotion for $340 right now I believe.



Other things you can do for the cooling system would be to get a high pressure rad cap like Greddy or Mazdaspeed 1.3 bar and flush the whole system and run more water. I run 80% water to 20% coolant in the summer.

 

yah, dont remove the t-stat. it also needs it for backpressure so the coolant reaches all the coolant passages.