Help in tuning out (SLS,Ruf,etc..)

[andmen]

I have a fully modded SLS that i drove on the Nring with TC set at 3 (everything else is off bar ABS which is set =1). When i brake, the rear end comes loose and the car is just very nervous despite being on racing soft.

I have the same pb with the Ruf BTR.

What should i do to make it a little less nervous. I dont want to brake early..

 

[andmen]

It also understeer, but i guess that thes TC @ 3.