I've done the B-Quiet thing AND the exhaust wrap
Last summer I put a layer of Brown Bread topped with a layer of original behind the seat. I then put a single layer of Extreme in the doors. The two helped some. The biggest thing I noticed is it made the stereo (after market CD and door speakers) sound better - really helped the low end.
Last weekend, since I had a bunch of Brown Bread left over (2 rolls for the price of one - but that's another story), I did a double layer from as far up the fire wall as I could reach under the foam padding that is in that area all the way back almost to the back seat. I also did a double layer of 2 inch wide header wrap from the tubo to the muffler (almost 120 feet).
All said and done, it helped a little - sorta mellowed the sound, but you can still hear that mighty 6. I don't think anything short of earplugs will eliminate it completely. That's OK. Hey, its a diesel!
Jay