Coilover Adjustment Question

Hey,

So I have hsd monopro 12/10k coilovers on my 99 Lexus IS200. I have lowered them to the point where the rear springs have 1-4cm(i don't remember exactly) of free play when the rear is raised into the air, I did this so I would get my desired height. I didn't really see any issues, except when I lifted my coilovers by 5 cm, the whole suspension had stiffened up quite heavily, so now I'm trying to figure out what I could do to keep that stiffness which I had when I raised the car, but with my desired low. (fyi, the front springs have no free play)