Vehicle appearance is improved in two ways. Sport springs will typically lower vehicles to give them a more aggressive stance and reduce the vehicle's fenderwell gap (the distance between the top of the tire and the edge of the wheelwell). When the vehicle is viewed from the side, the wheel and tire will appear to properly "fill in" the wheelwell. But when the vehicle shows fender well gap, it may look out of proportion and even create the illusion that the vehicle has been "lifted." Sport springs complete the vehicle's appearance by lowering the vehicle and reducing fenderwell gap.
Vehicle performance is also improved by sport springs in two ways: they reduce ride height and have higher spring rates that are carefully tuned to the vehicle. This ensures sufficient load capacity and lowers the vehicle's center of gravity for added stability. It also improves the vehicle's responsiveness by reducing body movement, allowing the tires to function more effectively when performing at their limits.
Another solution is a complete coil-over system that combines springs and shocks along with an adjustable perch to support the spring. This set-up is most like a race set-up in that it allows tuning of the vehicle through ride height adjustment.