what is the effect of lengthen rear camber link?

[gtimax]

lengthen front camber link get more front grip right?
then what is rear effect?
I am so confuse that some setting effect on touring car is opposite with buggy(I start with touring, just begin buggy)
I know lengthen the rear camber link will make rear end roll more but rear roll more would increase rear grip or decrease?
thanks again and again!