Some here may have other opinions but mine would be NO, stick to 7.4v LiPo
A 7.4v LiPo will still perform a bit better than the stock battery.
It would probably work for a while but its not designed for that kind of electrical power.
The motor will suffer, no MOSFET so the trigger contacts will arc like crazy, the gears would have to be well shimmed or get chewed up and the bearings would take a pounding.
Something will fail sooner rather than later and when it does it won't be pretty.