I mentioned in another thread about the oil some of us use here in the US on our Harley transmissions and what has done wonders for reducing the 1st/5th straight cut gear noise has been Redline Heavy Duty Shockproof gear lube.
It reduced the noise in my trans so much it's hard to tell 4th from 5th gear anymore.
I'm not sure how much it will reduce noise in the M3W's, but if you're going to be changing the box lube, it might be worth a try.
Very nicely detailed procedure with great pictures.
