Disappointed with my new mega...should I be?

[speed demon]

I was running a medusa 36-50-2200V2 with a 4S 5000mah in my rustler. I went from the stock vxl motor and esc on a 3S 4000mah and going to the medusa and 4S I noticed alot more runtime(atleast 40% more) and very cool temps. I figured more is better so I bought a mega 22/30/2 1770 with a 5S 4000mah. After running a few cycles and doing some speed runs geared 23/76 I had to stop alot to keep the thing from getting past 140 which I was told the max.

I then threw the 4S medusa combo back in to check the temps and they barely broke 100 most of the time I checked it was around 96(64 temp outside). I just don't get it to me the run time should have increased some and temps would still be cooler then my medusa. I could gear the medusa 30/76 and not have a problem and run cooler then the mega did on 23/76 gearing.

I'm not running a fan since I broke it but would prefer not to even run one. Now I'm thinking to just get a medusa 36-50-1600v2 and use this 6S 4000mah I have coming tomorrow.

The MM never even broke 100 anywhere on it; I do run a fan though.

Any thoughts would help.