I also read the article in Diesel Magazine. And according to that it said its a 100% CNG and not a CNG and Diesel Fuel Mixture. I have been doing some research my self and the kit from PDI cost around five thousand. But then you have to either buy the compressor to put it into your truck that costs another couple thousand, or if you live in California I believe some of the fuel stations offer CNG. All in all if it does work the way they say it does then it would be a investment that I would be thinking about down the road. This is a link to the people that they bought the CNG equipment from....
http://www.pdidiesel.com/