To answer any questions about the "biggest" motor that will fit... It looks like it was designed for up to a 2838 but this 2845 will not. I notched the ESC plate to make the 2838 easier to fit without removing it. I have interference in several areas with this 2845 including the chassis mount for the ESC where it hits the screw mount, the ESC plate (though likely okay if the ESC mount was shaved), and the wires are a TIGHT fit. You could probably mount the motor with the wires 180 deg from the visible position but then they would need a 180 deg bend out of the motor....
I have a 2838 4500 kv ebay motor that runs pretty well and cool with a 17t pinion. The x1401 2938 Tenshock motors appear to be a popular option with the LC racing crowd but I would be surprised if they fit ours. For those that have not investigated, there is a small plate to be removed around the center dog bone to allow the bigger motors to fit. It works great with the motor mentioned but is VERY close when gear mesh is set. I would imagine that it would not mesh correctly with even the 1mm larger motor unless you started grinding or used a bigger pinion.