If you are trying to keep peace in the neighborhood, the best noise reduction for the dollar is the oil pan blanket.
When I created my own oil pan blanket, I was amazed by the reduction in noise when I walked away from or up to the truck. There is ALOT LESS rattle and clatter coming out from under the truck.
The next item I would try would be to insulate the sides of the hood, and the inner fenders and maybe the back side of the fender liners. With glued on foam, or maybe with a spray on product like used in the truck beds.
I have done a lot of work on my truck to quiet it down, and while there is a big improvement, it still is about like a powerstroke, not like a Duramax [yet, I'm still working on it]
Inside the truck, I'm about at Chevy Duramax levels. I bought a DB meter the other day, so I will try to get some readings to use for comparison for the 'numbers guys'.
If you are interested in trying to make a sound blanket yourself, I'd try the sound barrier product from
www.soundstop.com It is a 1/2" multiple layer foam with a dense lead like product between the layers, weighs about a pound per square foot!! The name of the company is GSI, and I spoke with Don, and he was very helpful with my ongoing 'Operation Quiet Cummins'. I negotiated a 15% discount for TDR members, so just mention the club for the discount.
Hope this helps Greg L
Attention: TDR Forum Junkies 
