Solid bushing set improves roll center by raising up the inboard suspension mounting points on the subframe. This also improves the axle joint angle on lowered cars, prolonging their life. Spacers are provided in case you need to keep the subframe in the original position, if rules in your racing series demand that. Check the gallery for install photos. This CNC lathed, Anodized aluminum parts set was designed for optimized fitment and ease of installation considering OEM chassis and sub-frame manufacturing tolerances. This set fits perfectly without a press needed due to our precision measurements & manufacturing however you may find that a clean subframe free of rust & freezing the aluminum parts before knocking them in with a dead blow hammer will help your install. If you get these, its a great time to also install our aluminum solid diff bushings, sold separately. Some people with older cars actually get less noise from the drivetrain because they didn't realize just how bad the original bushings had become despite solid mounts naturally transmitting more noise than rubber.