Thanks to Poor Boys RC speed challenge, I got this idea. It reuses stock MF-01 34T/24T spur gear in place of the original 37T/21T, to achieve lower gear ratio.
The mod supports 21-33T pinions with FDR ranging from 4,44 to 2,83. Its real-world capabilities weren't tested yet :)
Use M3x10mm screws to mount the motor. You can use 10mm dia spacer to avoid deformation of the motor mount. The mount should be printed out of high temp material like ABS or ASA.
The author remixed this model.
Alternative motor mount and gear cover.