I have been doing alot of research on this myself. I just purchased a 08 2500 crew cab long box. Seems the consensus is distilled water and KOH is the ideal. There are many respectable companies out there that are doing this. My worries are that the truck is brand new and I am not sure what the implecations would be if cought running it.
From what I have found you can receive a IRS tax credit for running any HHO generator on your vehicle. Unlike some states who jam it to the veggie oil runners for not paying the gas tax and claiming the credit for veggie oil, you can not get stiffed by the government for running HHO.
Following are excerpts from IRS Publication 535 :
You are allowed a limited deduction for the cost of clean-fuel vehicle property
and clean-fuel vehicle refueling property you place in service during the tax year.
Clean-burning fuels. The following are clean-burning fuels.
1. Natural gas.
2. Liquefied natural gas.
3. Liquefied petroleum gas.
4. Hydrogen.
5. Electricity.
6. Any other fuel that is at least 85% alcohol (any kind) or ether.
Deduction for Clean-Fuel Vehicle Property
The deduction for this property may be claimed regardless of whether the
property is used in a trade or business
Clean-fuel vehicle property. Clean-fuel vehicle property is either of the following
kinds of property.
Any property installed on a motor vehicle (including installation costs) to enable it
to be propelled by a clean-burning fuel.
Note: You will still need to consult with your tax advisor to ensure this deduction
applies to you.
One of the companies that I contacted said they are working on systems for the 08 Duramax. Appaerently some changes made recently, unsure what since I am new?
Also, for those making the systems, be very cautious of PVC applications. Holds the heat and melts. Bad Ju-ju.
Here is a very professional company and system I am looking at buying. Don't have the time or brains to make my own but I do agree it is simple.
360 lph HHO Booster [Alexis X100 kit] found at
HHO Store Alexis X100 HHO Booster Kit by Hydroxy Technologies HHO Kit Hydrogen Cell Store.
Or:
Zen Cart!, The Art of E-commerce
Big rig over the road diesels have been using this for awhile now with documented increases of 20-50% Some of these guys are going from 3 mpg to 12mpg. I have seen 05-06 modified fords getting 30mpg to 38 mpg.
Almost all the guys running the systems advise or say to get the full benefit of HHO you need to be able to lean the fuel down and trick the ecu when the O2 sensor calls for more fuel. This is the secrete to maxium increase in mpg.
This site has an oil additive that is suposed to ward off an side effects of the HHO injection. Go to the bottom.
Hydrogen Generator for Diesel Hydrogen Injection (541) 255-2493
Comming big recently on the market is dry cell technology for these. The HHO generator at the above link is a dry cell. Metal looking box in bottom right of pic.
I believe this is a very viable option to increase fuel effeciency. My dream system would be my truck with a magnaflow big pipe and muffler delete kit, the Alexis X100 kit and some kind of performance chip. Although I do not know if one would be needed. Can anyone help me

out with this huge puzzle I have.
If your system is getting to hot
check your amp draw or your electrolyte mixture, could be wrong.
1. Is it wise to do it on the new truck. The tax credit would pay for it in the first year alone.
2. I am not aware of any HHO complications. Are you guys telling me something new?
3.Help. I just need some flat out help. Had a mechanic tell me not to do this until I reach 1,000 or 3,000 miles. To long to wait