he Perrin Positive Steering Response Kit (PSRS) for the Subaru WRX/STI is an anti-lift kit (ALK) designed to prevent lift under acceleration in cornering. The PSRS relocates the rear mount of the front control arm, increasing the caster angle for better turn-in and response. This design will also control wandering from uneven pavement or larger wheels and tires. Perrin has recently redesigned the kit to use Delrin bushings for zero deflection and elimination of noise for trouble-free operation. The 6061 aluminum housing makes for a strong, precise part. A 10-15% increase in noise, vibration, and harshness should be expected as the stiffer mounts absorb less road noise.
The poly bushings upgrade (sold separately below) can be used with the PSRS system to reduce noise and harshness. If you find the PSRS is a little too stiff for you, these can be used to soften your ride.
Subaru STI 2004-2007
Subaru WRX 2002-2007