For 13.5T blinky, target roll-out at about 85mm, for 10.5T blinky, 55mm. We cannot give you the size of pinion without knowing the rear tire diameter, also, as your tires wear, you will need to adjust your gearing to maintain the same roll-out. I would recommend getting some smaller spur gears as well for the higher turn motors(and for the mod., as the tires get smaller, you may not be able to use the 96T) For 13.5 and 10.5, get a 76t spur, for mod, 88t-92t spur. Then get pinions from about 25t to 52t.

Roll out is the distance the car will move with one revolution of the motor, to calculate roll out=3.14*tire diam/(spur/pinion). Or go to GEARCHART.com to figure out gearing.