Intrax springs have a barrel design, where it has a number of softer coils which are always fully compressed to compensate for a shorter length and provide some preload when the car is up in the air. The downside is that there's only a couple of coils left uncompressed, which limits the suspension travel, and the ride suffers a lot. Eibach, on the other hand, uses a progressive design, where the thickess and stiffness of the coils varies through the spring length. It employs all of the coils at various stages of the suspension travel, which allows for a much more comfortable ride without having to make the spring too soft to sacrifice the handling.