The Whiteline rear subframe lock bolts for the Subaru WRX/STI will remove the slop from the rear end. The WRX and STI have a rear subframe that is held to the car using soft OE bushings that allow movement. This excessive movement reduces the effectiveness of sway bars, lateral links, and control arms. This inexpensive kit from Whiteline threads bolts into holes that already exist from the factory. The bolts install simply with hand tools and will stiffen up the rear end of your 02-07 WRX or 04-07 STI.
Subaru STI 2004-2007
Subaru WRX 2002-2007