Iv seen that bokchoys link but it's USDM cars only, and they don't have any of the baby engine beemers over there :L

Iv looked into the quaife diffs alright but I really want a plate diff rather than a torsion style as the quaife is, so far my best bet seems to be m3 which is doable just need some extra bits but my main concern with using one is the ratios, my little 325 is a bit shy of a V8 so I need to figure out my best bet ratio-wise and maybe pair a better ratio wheel and pinion with the M3 LSD.

It's a crime modernish Beemers mostly use open diffs!!