Is this true? What's the real difference between the two? I am trying to figure out what kind of springs I want to get for my GT. I was looking into BBK springs maybe later on.
progressive just means that they are not there full rating right off the bat. as you brake and the coils compress they get stiffer. so they have kinda a softer ride but in tight corners or heavy acceleration or braking they have there full lb rating.
That (edit: 86bluecobra's reply) is correct. Progressive generally allows for a more comfortable ride when load is not high on the springs. When you launch, corner, brake, etc, more load is put on the springs and they respond with the higher rate.