Blackcat,
It affects ALL E46s. But the M3s get it the worse (01-06) because of more power.
Just try searching for "subframe" here :
http://www.m3forum.net/m3forum/search.php
And you'll see how bad it is. For those in the US, they can appeal and have BMW themselves fix it for them.
Unfortunately for us, we have to get it fixed ourselves at our own expense.
The TMS rear subframe kit is tiny. You should see Ruben or his father at Tedco, Segambut.
They have very good experience with this. I did mine there and I was very impressed at the quality of the work done.
The plates and welds are very chunky, it fills the 4 point of the body so any force will be spread evenly.
They prepare race cars for a living so I'm very confident leaving my car there at the time for them to work on it.