there was a lot of talk on yt about this recently.. how adding spacers to progressive springs would make it undriveably stiff and would just result in you switching the springs out.
however, a yt member said hes been running a daystar spacer kit on his pp springs with no resulting stiffness...
apparently the daystar is particularly good for this application.. and it comes in i believe 3" and 2.5" form....
so, ebelen, im not sure on your spacers, but i know that at the very least daystar spacers do work with pp springs. my assumption is that the ride may stiffen, but not as bad as a lot of people would think. most of the naysayers have no experience with either pp springs or pp springs and spacers.
ill letcha know how i like the ride when i get around to ordering and installing a daystar spacer kit.