Detailed pics on page 7.
Since my original Quaife fitted diff got damaged due to poor workmanship I decided to have my tuning shop do what I was told was impossible. I decided to give it a shot and fit a E90 M3 diff. Since everyone said that is was not possible and after viewing a couple of photos on the forums of twisted side shafts I decided that it would be worth the try.
The final drive on this diff is very short 3.84 so the car really kicks when it is on the go. Off the line I can say the car has not really benefited but I am yet to VBox test to confirm this. On the roll it is really impressive with immediate thrust in any gear in comparison to the rest of the gears. The biggest benefits are in fifth and sixth where the car closes the clock easily.
My intention is to now test various final drives as they are readily available for the M diff.
In terms of traction and handling I can say that the M diff is far smoother than the Quaife. Power delivery can only be described as much sharper. I have done close to 2000km now with this diff and can say that I personally prefer it to the Quaife.