A guy at my track runs the same speedo, and he is using a LRP X12 17.5T - that thing is a rocket down the straight, and it got plenty of rip in the infield. He is using timing-setting 4.
I personally run the Speed Passion V3 motors, which work really good for me - low temps with my Tekin RS Pro, and plenty of speed for me.
Team TCHobby / Team Upgrade-RC
Tamiya TRF417 / Speed Passion GT2.0 / Speed Passion V3 motors.