This kit changes your front suspension geometry by lowering the pickup point for the lower control arm. The result is a decrease in the built-in anti-dive/anti-lift geometry effect, meaning your front-end will stick more in both acceleration and braking modes.
The mechanics are a little tough to explain, but in short the front wheels will droop a little more on acceleration (making the front end stick more), and the nose of the car will dive a little more under braking (again making the front end stick more). This makes your Subaru more neutral and less prone to wash out the front end under hard cornering when braking or accelerating. Polyurethane bushings help to further firm up steering response in the front end.
These fit the 2008-2014 WRX and 2008-2010 STI only. Does NOT fit 2011-2014 STI.