Mechanical brake / Castle Neu problem

Hello again everyone :D

I have a question regarding the gearing on my setup now. Im currently running the 12t pinion with the stock 50T spur, which performance wise is working perfectly. Similar, but faster to my nitro car, and no crazy wheel ballooning etc.

I measured the temp of everything after my last run, and found that my motor was fairly hot when compared to the ESC and batts.

The ESC was about 30C, the batts were 33C but the motor was just under 50C (degrees in Celsius).

I looked up the thread on motor/speed/batt temps which has

Hot motor, cool controller, cool batteries = undergeared
Cool motor, hot controller, hot batteries = overgeared

So I guess my setup is currently under geared. Does that mean I need to go up a couple of pinion sizes to "gear up", or does it mean that I need to go down a few?

Thanks guys :D