Lowering springs utilize your factory suspension components, just replacing the the springs to a shorter spring thus dropping your car. But just installing lowering springs will affect the stance of your car, your toe will change your ride won't be like it was, a coilover setup will correct all that and lower your vehicle the proper way and replace you shocks/springs all together. Also giving you control of height adjustment as you please from moderate drops to extreme drops without affecting your ride like lowering springs do on really big drops, as well as giving you the ability to adjust dampening from hard to soft ride depending on the coilover kit you buy, BC come with adjustable dampening, some come with a preset dampening to a factory like ride setting. I don't know if I missed anything in there...but we'll leave it at that..
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