COILSPRINGS to AIRSPRINGS Most compact and Euro cars have struts on the front, and coilsprings with a separate shock absorber on the rear.  To determine what diameter Air Springs you need, measure (MAKE ROOM) and make room for the largest diameter possible. VIEW BRACKET CONFIGURATIONS HERE.  The larger the diameter, the less psi it takes to lift and your ride is smoother.  In some cases, you will have to move a shock absorber or relocate whatever is in the way to make necessary room.  We automatically make the brackets to drop you 2-3 inches, so if you want to maintain factory ride height, you must inform us at time of purchase.  You can also choose to go 2-3” higher for ride height.  Ride Height is the intended driving height.  It does not mean it will not go lower, or higher, it simply means that is the height you are going to align your vehicle to.  If you plan on a ride height lower or higher than 3” you MUST have new upper Control Arms, preferably both upper and lower .  Control Arms compensate for the change in Geometry.  If your factory shocks are in the middle of the factory coil, you will need a Shock Absorber Relocation kit .  In any case, you will need new shock absorbers (shorter if lowered, longer if lifted) to compensate for the change in shock absorber length.  Review the Generic Instructions on this link to see how to install the brackets.  Scroll down to find Bags/Brackets install.