I just had the rear axle M3 mounts bushing(s) replaced in my 135i. It really transforms the way the car drives/rides for the better. Gone is that wiggle and rear axle movement. The car fells so much more planted and secure. Here is my writeup...
Dackel's replacement of rear suspension OE bushings with M3 ones…
http://www.1addicts.com/forums/showthread.php?t=638163