I have a diff installed in the rear and the more I run, the more use I see out of it.
You can customize it according to the tracks layout to benefit your particular drving style. You can completely lock it up if that's what you want of have it as lose as a goose.
Only track time will tell you whether to tighten or loosen it. I run mine pretty tight ot rather locked up.
I have one in the front end of the same car, more for bling than practicality, since I have it locked up tight [used the one way on my current racer, since I retired the car with the active diffs and only run it fro demos and fun].
I wish I could explain it to make sense but go to the experienced guys at the track and they should give a good start point. And as Darryl Waltrip says "sperience will teach you". If you want to start in the middle you can feel/see it for yourself. Remember, puting the power onto the track is your goal in cornering.