Another Duramax website is "dieselplace.com". It's free but, you do have to register to use it. No big deal.
Two of my friends have Duramaxes ('03 & '04). They love them! I've got to admit that they really seem to respond well to fueling upgrades (boxes). The '03 had a Duramaximizer & Duramaximizer Tech 4 and is quick. It gets terrific fuel mileage (25. 5 mpg on the hwy. , sometimes, hand calculated).
The '04 has the Edge Juice/Attitude and runs well, also. Seems to be quick, to me.
You have to be careful with fueling upgrades so as not to compromise the Allison, like with all auto's. The '03 is on its second Allison.
The '04 is never run over the "2 setting" so as not to hurt the Allison. It's pretty fast on the 2 setting and there are 5, altogether. The '04 gets a little over 20 mpg's on highway.
The '04 is, also, having problems with the tow mirrors. Some problem with the gear that extends the mirror, I believe.
The Bilstein's are a good idea, also. Made a big difference on both trucks.
Personally, I think the Duramax/Allison's are better than I had expected them to be, considering GM's previous diesel attempts. There are guys towing professionaly with them and not having any more problems than anyone else. I, also, think GM is taking care of its customers by providing an extended 200,000 mile warranty on the engine. They are, also, making more of an attempt to offer better fuel filteration with a dual element fuel filter (5 or 7 microns, I believe).
Aparently, the GM Employee Discounts are a good deal and they are selling the hell out of them.
I still like my Dodge/Cummins trucks. However, I've been having some injector issues which I'm having a hard time getting DC to take care of. You have to go through a "chain of command" to try to get anything done. I wonder if GM would respond better?
Joe F. (Buffalo)