[hailmick]

just grab as close to 5000mah 4s lipo 25c you can afford
5s would be better but your mamba max may become unreliable
offshore electrics states that your 9xl has max amps of 74 but that will spike now and again
and your mamba can handle it so long as temps are good
their are other people on this forum that run their revos on 4s with mm and 9xl's maybe they will chime in
also is it a converted revo or e-revo