I would think you would be pushing the esc beyond it's limits.
It might be possible with the 4 cell nimh setup? But I have to wonder what kind of performance you would get?
I know in brushed mode a Mamba 25 can run a 540 Silver Can motor with no problems. But of course this is not a high performance 540 brushed motor or even a 540 Brushless motor.
I have seen a guy using a Mamba 25 with a Feigao 380c 9t brushless motor in a B4 with 2 cell LiPo. So it might be possible?