Yes the springs are really firm. Thats why I sold them, because I live in vermont and the roads are all beat up here. I had that happen a few times in the back on large bumps. I wonder if matrix sells an extender or some other part you could throw in there to keep that spring seated. The fronts do not have the same problem, but are really firm as well. I didnt need the spring compressor to remove either the front or rear springs if i remember correctly. I'm sorry if they are too short/firm for you. I was trying to represent them fairly, but I didnt know excactly what i had because I didnt buy the kit. thats why i sold them at a low price. hope they work out for you.
I put the fronts on today and they were a lot smoother. So i redid the backs cutting off the stopper a couple of inches and no more bottoming out.
Right now I am pretty happy with them. Sure they are stiff, but the car is about 4 inches off the ground.... I did an aero measurement today but have not processed it yet. more later.... but getting them installed correctly was part of my issue. need a camber kit for the front now though.