For on road use you will want little to no preload, essentially start with it as it is. You can also swap plates and remove the spring plate and swap that for a flat. This way under light throttle it will open fully but it will come in fairly aggressively when you apply power. This can induce understeer till you lift throttle, can be a bit unsettling.
If used primarily off road you want to change the stack to get full grip. To me I still prefer low preload but you do want the spring plates in it still so it will ramp up when a wheel lifts.

There is a Mazda RX7 torsen diff that with some machining will go in the front of these as well.