Thanks all for the help. As I went looking for a new vehicle I was sure enough improvements had been made since I bought my 02 2500 with a V8 Magnum (5.9)that I seem to get 13-13.5 hand calculated that it wouldn't be an issue. I have more than enough power with the 5.9. Dealer told me what he found was a 5.7 and having more than enough power with the 5.9 I thought the 5.7 would suffice. Then I found out it was a 6.4. That's when I got concerned. I'm still on the fence this morning as I can back out of this deal. I'll tend to keep trucks for their life time and want to be sure I don't make a large fuel mistake.