With the FR-S / BRZ MacPherson strut design, the entire vertical suspension load is transmitted to the top of the vehicle's strut tower. For this reason, there is inherent flex within the strut towers relative to the vehicle body. During performance driving there is enough flex to alter what should be static camber, toe, and caster settings. This change can make steering response and body roll more pronounced and unpredictable.
The PERRIN Performance strut tower brace solves this problem. During cornering the PERRIN strut tower brace transfers the load of each strut tower via tension and compression of the strut bar, to the opposing strut tower, reducing flex by sharing the load and tying the strut towers together. The improved chassis rigidity enhances steering precision under high load conditions and reduces understeer.