You probably won't need one. I ran one last weekend in a TC3 and the hottest it got was around 125. The weather was cool (maybe 60 degrees), so I tried gearing up a tooth or 2 every round, and eventually got to a point where it apparently reached the limit of available torque and went slower. It still didn't get very hot. The final gear ratio that seemed to work the best was 5.6 to 1.