Stock springrate L7

Hi peeps!

Does anyone know what the stock spring rate is on the rear springs of a Cuore/Mira L7? I’m currently using the BC racing set, but the rear is way too stiff. Both front and rear have a spring rate of 4k, which is fine in the front, but awful in the back since there’s hardly any weight. I’m trying to get a number between the stock spring rate and 4k, so I can get custom made springs.

Thanks in advance!