When using the car on track it is impossible to setup proper rear aliment with OEM arms. The more stress you put on the OEM arms the more the rubber on arm compresses and you loose what was very precisely set during car alignment
When using the car on the track the cornering forces are bending the rubber in the wishbones. This can lead to slower track times and ineffective tire usage. For that reason Verkline have come up with uniball control arms, as used in the Porsche RS line (GT2RS, GT3RS). Tested intensively.