Now here's an interesting thought.... My E36 (325tds) does this too. It's only done it since it was chipped and none of the gears slip at all, is your 316 chipped?
There is the occasional knocking noise that can also be felt through the gear stick when in neutral and moving it toward the pasenger seat.
One thought I had is that this could be exhaust pipe judder that is transferring to the change rods as they are pretty close and I did have the exhaust off recently to bash out the cat.
@ 96_323: Having said that - your comment about a 1st cog on the way out sounds worrying :/
In any case, no slipping in any gear. Car runs a beauty. Just kangaroos a bit in 1st.... this can usually be solved by getting the revs up a little before letting the clutch fully engage.... I want to say clutch - but no slipping? Confused.
Talking of MAF, my car returns these fault codes (at least I think they are fault codes, I got them from the OBC - I think one is MAF - any ideas?