the way it works is the computer senses 1 wheel spinning so it applies traction control to limit the spin thus the 2 black marks. if you examine the marks and the rubber in the wheelwell you will see the drivers is darker and more rubber there. its not equal to each side so the lsd fixes it.
tom2112 is it really to expensive? 2k for rims 800 for dual cai 800 for tunes 1k for tires, you get my point. the cost is relative to the fun you want to have with the car. all toys are expensive to some regard.

jim i apologize for jackin your thread!! fellas all the q's on the diff can be asked on the 6 forum