The links replace the stock links between the ride height potentiometers and their respective suspension arms. The stock Tesla pieces are of a fixed length while the adjustable ones have ball link ends on a piece of threaded rod (with lock nuts). Changing to the adjustable links allows the owner to change the perceived ride height thus fool the active air suspension to a different ride height. Beware that (1) lowering the car increases negative camber which is tied to extreme tire wear in the rear and (2) the suspension lowers further at speed and you do not want the car too low going down the highway (so care must be taken on how much you lower your car).
Non-active air or coil spring cars will require a change in springs to get the desired results. Normally you would have springs that are wound with a higher spring rate in addition to a shorter installed height (to lower the car). The added rate prevents the car's suspension from compressing too far under bump loads and does affect ride quality a little bit. I'm not aware of anyone that has done springs for MS but it is not a difficult task to have Eibach or a similar spring company wind a set of springs for you (if they do not already have something done). I've had springs made for race cars in the past and they are surprisingly affordable.
