I'm on the newest Ohlin's street tune with 7k front/11k rear springs at factory MYP ride height.
Yesterday with 4 people and some luggage we just touched the rear bump stops on a bigger freeway compression.
IMO 8k rear springs are too soft, especially loaded. You would need to increase the damping quite a bit for it to work and the ride would be harsher than stiffer springs with proper matched damping settings.
7k front/10k rear is probably the perfect comfort setup without compromising sporty driving. This is at MYP stock height. At LR height 6/9k would be even plusher.
I ordered a smaller front 28mm sway bar from a base model 3. The stock 31mm adds about 3X the wheel rate with single wheel bumps and rocks the car far too much, especially at slow speeds. This will be a 40ish% reduction and provide a lot more front end grip at a small expense of turn in. The balance of the car will be shifter rearward for more neutral handling. Normally I increase the rear bar for balance, but I think a smaller front bar will pair with the stiffer springs much better.
The model 3/y need far more spring than factory for heave and pitch. The stock suspension relies on super long bump stops to add (non linear)spring rate, overwhelming the dampers.