The brace connects the two shock absorber mounts. In a hard corner, the loaded suspension tower pushes outward and the geometry deteriorates precisely when you need it most: the brace distributes the load between both sides.

The front end feels more precise on turn-in, and the car maintains the same response from one corner to the next. The effect is noticeable on older chassis, convertibles and high-mileage cars; it is more subtle on an already rigid modern body.