The standard anti-roll bars are fine for the average driver but when cornering speeds start to rise (due to more power or suspension upgrades) the body roll will be more noticable than before, which will result in a reduction in tyre contact on the road surface.
This will increase the load difference between the wheels on different sides of the vehicle, reducing the grip on one of the sides and potentially resulting in wheels spin as you power out of the corner.
Stronger, stiffer. Reduces roll, increases grip. Includes front and rear anti-roll bars, the front is 26mm thick and the rear is 20mm thick.