Originally Posted by sosidge
They do work as a progressive spring because the pitch (the gap between the coils) gets smaller, this means that under compression a few coils become coilbound, making the spring feel gradually stiffer.
the few i tested are dual rate (nothing gradual about it), and they didn't get to the second rate until around 6mm compression, likely making the second rate unreachable when used on the car.
so, in reality, all anyone was doing when they ran those were using the first linear section which was presumably way softer than what they were comparing to. hence the laziness
, which was the popular comment on them. (this also matches up with what a true progressive spring should feel like given the same end point in body roll, and is probably accountable for why so many people thought these were truly progressive).