I went from a '02 7.3 to a '13 6.7. World of difference. Much, much quieter and the power available is still putting a smile on my face while towing even two years later. Other than paying for it I have no regrets. Getting about 1mpg better in daily driving, and perhaps a half better towing.
On hills that would have the 7.3 wide open at 62 the 6.7 stays in high gear at 70 and I can pick up speed, especially if I let it drop 1 gear to 5th.
I've had a couple things done under warranty - EGT sensors (2) and a water pump at developed a weep at the shaft. Had the DEF gauge get out of whack and the dealer reset it for me; I've learned to wait til it asked for fluid and all has been good. 44k on it now.
One thing I was REALLY disappointed with one the '13 is the **** shocks. Totally shot with just over 20k. Actually caused the front tires to cup.
The newer front suspension is really nice too compared to the leaves on the '02.
