Anti roll bar, its all in the name to be fair. Its a BAR, thats connected to both wishbones at either end, with it being fixed to the subframe that assists in stopping the natural ROLL of the car when cornering, hence an ANTI device. Upgrading means fitting a bigger bar with more torsional rigidity, hence stronger which means less roll. The rear S3 ARB is laughable, its like a toothpick!!