The stock motors are really useful, however, so far they seem to me like they can very easily violate the conservation of energy. I don't know what the units for 5000 torque are, but I do know that a pair of stacked motors consuming a combined 290 kW seem to be able to deliver much more than 290 kW of mechanical power. Probably more like 10s of Megawatts.
Free energy ftw!