Mate you are wrong the the slipper can help on any surface if it's flat polished high grip it all helps you can use the slipper to smooth out the aggresive ness on acceleration and also aid the car when on the brakes.
Set your diffs up to be free but tight and have a play you will find a sweet spot where the car just feels smooth on and off throttle and on the brakes.
Stu
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