You are right about the progressive vs straight coils. That is one reason I went with the PP springs. I also wanted them for when I tow my trailer. I knew I would never put a spacer lift on my truck, mine is as high as it will ever go $$$. Also, it helps when you get all 4 PP springs used for only $160. I could not afford them new. The PP springs are best utilized with the Bilsteins, I think. OME's seem to work best when you use OME springs and shocks from what I have heard.