One last thing...
The less difference between the inside and outside wheels at full lock, the less the inside wheel will drag mid corner.
The less grip the more difference you normally need for on-power steering, due to the tires slip angles. For rubber tires usually upwards of 1.5d to 2.5d difference works. For foam tires usually only 1d to 2d difference is needed.
You'll find out how much the inside tire drags really quick if you have a one-way up front.
Too much drag = abrupt mid corner oversteer.
With a front diff you don't get oversteer and the problem is somewhat masked. You can mainly tell when following a well setup car as your mid corner speed will be much slower than the other car.