Hey nuz69, I bought this combo in October and ran it at a semi heated indoor clay track. The pits are heated and the track is not. I talked to tech support at Tekin and they said it is close to the limit but still ok. Upon further inspection of the rear diff, there was a little play between the gears which I just reshimmed to fix it. I guess I could try to run with a 15 tooth pinion and try that. I previously had a MMM 2200 on 5S on the outdoor track and was used to those speeds running 14/45. Guys, I really appreciate all the advice given so far. You guys rock!