If you want to get more run time, try to use less % nitro. I try to use 10% nitro on my ATX, with the standard 75 cc fuel tank it run for 9 minutes 58 second compare to 6 minutes 12 seconds using 16% nitro. Using OS#8 plug, HSN 1 7/8 turn ccw, LSN 1 turn ccw from fully closed, the engine temperature is 232 - 246 F in average. So far, I could not see any difference in performance. Next Sunday, I will race using 10% nitro to see whether I can beat other car which use 16 - 20% nitro. I believe with 20 minutes in Main I can safe about 16 seconds by less refuelling.