I have not had the noise, but have previously owned cars with NOISEY diffs (the GT3 for one). This is a "normal" noise. Most diffs with higher lock-ups will make some noise, its the nature of the beast.
I am with Radiation Joe on this one. I would not add a modifier to reduce the noise. IMHO, you are retarding the effectiveness of the clutches....and thus, the overall performance thereof. Personally, I would live with the noise.
Now, for people that are basically city drivers that do not track, etc., it is really a moot point as you wont notice a reduction in lock-up in most cases. So, if that is the case, and you dont like the noise, go ahead and add it. Either way, the diff will still be under warranty.
Tim <--- apparently likes "3" cars
2014 MB E63S
2008 E90 M3 -- Selling
2004 GT3 -- Sold
1997 M3/4 -- Sold
1995 M3 -- Sold