R56 Spring Rates?

to answer your question this forum might be able to better help you
MiniTorque.com

My nominal opinion

I would not mess the springs. I have stock springs and when it is all said and done the ride is hard. What I do have is hocthkis rear sway bar,eibach front sway bar, superpro a arm bushings with powerflex rubber washers, powerflex rear control arm bushings,powerflex trailing arm bushings, powerflex lower engine mount bushing with the metal tab out of the other engine lower mount bushing kit.Along with bilstien b6 shocks all the way around. The car is feeling every bump now. without the front sway bar it was slightly more comfortable. but now it is stiff . Makes a good highway car though!
to answer your question this forum might be able to better help you
MiniTorque.com

Its not a question of messing with the springs so much as understanding the difference between the OEM springs and the springs that come with coil-overs.