i have the mishimoto on my ST185 with standard green coolant and an aftermarket fan. (just a single one on the driverside of the rad). The last few track events I did were mostly 35-50mph and 90% in top of 2nd gear. in 80 degree weather and a hot track, I was only able to drive for 10-15 minutes before the temp gauge started going up (slowly). I think the problem is with overall airflow at those low speeds. The stock alltrac bumper is much too restrictive. I plan to get an ST185RC bumper and better dual fans to hopefully address the issue. I've done some hard driving at faster speeds (55-90mph) without any issues. hope that helps you guys.