Rear Suspension•
The biggest two things with the multi link on the e90/e82 to get more wheel travel freely is all the pivots resistance to rotating. I have read there the twisting of all those rubber bushings actually ramp the spring rate as much as 200 lbs. People "tune" the progression they want by installing different amounts of group n bushings.
I want my spring and bump stop to do what they are intended for. I also want free movement throughout the whole travel.
Lots of choices on adjustable arms. Some look like they have spherical bearings but are still actually rubber. LOTS are fragile looking, most all are aluminum. If you want durable which I do, moving to drift parts is a good choice. I found a company with all steel large diameter spherical bearing adjustable arm is a set of 3 pairs for the rear from
http://born2drift.co.uk for a really good price. They also have a great looking short shifter.
Second is availability of different rear shocks and later coilovers. That really requires a shock with an eyelet on the bottom. In comes the e90 m3 aluminum lower arms. I got a set of used ones off eBay for $150.
When all this comes in I'll put it down me and report on the freedom of travel.