I've been researching my suspension upgrades since reading this post and definitely agree with
nachob, you can see in their spec sheet the ohlins 1M kit has softer rear springs than their E9x M3 kit.
If you don't want to go back to stock, I plan on using the following components:
Ohlins R&T (BMZ MN01)
Ground Control street camber plates
stock sway bars
You might be able to get away with just replacing the springs with something softer, but I've read that the valving will be off on the dampers if you change drastically from the current spring rate. Measure the spring perch, swift should have something that fits.
https://www.swiftsprings.com/product...lover-springs/
I'm pretty sure this is a 7" spring.
https://www.m3post.com/forums/showpo...6&postcount=48