Spring rate is crucial in this instance as Pro-Kits are usually only about 15% stiffer than OEM; thus, you're lowering a car 1" (1.3" for the EUV) on the average but not adding much rate to compensate, so I reached out to Eibach directly for the rates on the Bolt EV/EUV kit. Here's what they replied...

FRONT: 200 lb./inch (linear rate)

REAR: 171-286 lb./inch (progressive rate)

This means the OEM rates are somewhere around just 180 lb./inch up front and perhaps 150-250 lb./inch in the rear rear. On vehicles that tickle 4000lbs. with people, that's monstrously soft! Annnd... When coupled with the underdamped rear chocks and the archaic torsion beam rear, this is why a lot of us feel a disconnect between front and rear (I think the front suspension design is brilliant (aluminum subframe and LCAs) for a MacStrut econo car.


Source:
https://www.chevybolt.org/threads/pro-kit-spring-rates-here.55469/