5 cell + mamba 25 in a tenth scale for racing?

I have seen a mamba 25 with a heat-sink epoxyed on the fets, looks easy just don't know what epoxy to use.
-do the numbers on the motor look reasonable? little airflow in truck compared to airplane, but not looking for monster power, just quick, smooth, and light.
-recomendations for a small light bec?-(so far found atlanta hobby park bec 6.5g (.23 oz.) 6v 1.25 amp cont. 1.5 amp 60 sec.?

-looking for more opinions on higher voltage being smoother? A high kv speed 400 size motor geared down on 3700mah two cells with my M.M. is an easy way to knock of some weight and safer, but then eventual monster/truggy/buggy will be stuck on 4 cell. 2-cell is lighter and cheaper than equal watt/hr 5s. mamba 25 ofsets extra battery weight compared to M.M. + balances out very well in touring car