DJ,
I'm running a 540C 9L, 9920, 4s lipo and weighing in around 10.7lbs in an emaxx. I was running the same gearing as you. 16/66. If your running the stock revo diffs and emaxx tranny your gear ratio should be identical to mine.
I was having all kinds of problems with heat and such like you with both the motor and the esc when I first set it up. What I wound up doing was going to 26/66 and run locked in first gear. (I still have the 2 speed tranny) This about the equivalent to 15/66 in 2nd gear. I put a small fan on both the motor and esc and now it runs almost perfect temps. Cant really push either one over 120-130, and the bats barely get warm. It has really nice speed and power for only a 9L
(
http://cgi.ebay.com/Small-Cooling-Fa...QQcmdZViewItem this is the fans I used)
Side note:
Cool thing about this setup is I am set for all around bashing in 1st gear, but then when I want to play around I can pop out the occasional speed run by just flipping to 2nd gear. No gearing set up hassles. It gets pretty hot in only 1 or 2 passes geared like that, and in 2nd gear, but its not meant for constant running. a pass or 2.... cool down. With that gearing I wouldn't recommend starting from a stop. get up to speed in first then shift to 2nd. Cant say that I can verify it (no radar or gps) but its gotta be toping 50 easy. Calculations say 57mph. pretty uncontrollable at top speed.