Here's a few more threads for the M3 arms (rear as well):
http://www.e90post.com/forums/showth...owerks+M3+arms
http://www.e90post.com/forums/showthread.php?t=230973
I do plan to change the rears when required but then I already have the diff lock, quaiffe, M3 subframe bushes, ARB and Ohlins too so generally the rear is pretty good now anyway.