Increased steadiness is the job of STI wing stabilizers. For competitive Impreza models, the spoiler actually plays a role. It assists with downforce on the track or road course. But on occasion, the wing can shake due to high speeds. STI wing stabilizers take away any movement that comes from constant acceleration. There is no more aerodynamic disadvantage holding up your ride coming off of corners. Because of this, it is crucial for professional racecars to be outfitted with STI wing stabilizers due to the constant strain on the back-end. But it is not just sponsored vehicles that are eligible for this modification. Even street models can benefit from what rear spoiler supports provide.
The intent is to reinforce areas where there is space. Perrin wing stiffis are placed underneath the spoiler and attach vertically. They behave as pillars, of sorts. Without them, at above average speeds the wing has a tendency to bounce. Perrin wing stiffis maintain better rigidity. Once in place, there is no more shaking or vibrating. The Perrin wing stiffis hold the entire unit still, allowing your STI to keep moving without interrupted downforce. The reduction in drag is noticeable on the racetrack immediately after installation.
Perrin wing stiffis have four sides but are not rectangular. Instead, they are molded into a trapezoidal shape that tapers from front to back. This helps the rear spoiler supports fit accurately between both wing levels without overhang. In addition, their shape also assists in aerodynamics. The rear spoiler supports are not bulky and do not take up unnecessary space. Rather, they are streamlined to promote accuracy as well as effectiveness. You can also choose how many you use. One in the middle should provide a discernible improvement. But you can go with two or even three rear wing brackets for both extra firmness and looks.
Toughness is important, especially for exterior parts. Subaru spoiler stabilizers are manufactured from auto-grade plastic and finished in black. You do not have to stay with the black finish. The supports can be painted to match your OEM color.