Well, I've had Ford diesels and I've had Dodge diesels in the past, but I've never owned a Chevy Duramax. After going back and forth with the dealers I ended up buying a Duramax last week and these are my impressions thusfar....

MPG:
This was honestly the main reason I wanted to get out of the truck I had. I do a lot of highway driving (70MPH+) and I was getting 11-13MPG unloaded. I'm happy to say that I am now getting 18-19MPG at the same speed and 20+ under 60MPH!! I was also getting about 7MPG with my trailer with the previous truck. I have not had a chance to pull with the new truck yet, but I will be doing so this weekend and hope to see more good numbers. I'm completely amazed right now because I have a little over 400 miles on my first tank and I'm just barely under the half mark...couldn't be happier about that.

Power:
I have to say I was initially somewhat turned off by the lack there of when it comes to tuning options available on these new trucks (I've always had my trucks tuned and modified). That is until I drove it...I was really impressed greatly with the power of the truck. The first time I was driving down the road and went to pass someone going a little slower than me my eyes lit up as it scooted by so easily....these things really do have good acceleration for a big truck...I don't think I would even be interested in modifying the truck if there were more options (well, maybe getting rid of the DPF...that's it though).

I'm also pretty pleased that I got a great deal on the truck trading in my LT model 1500 for an LTZ 2500HD. Well, let's just say my wife was sold from the start with the addition of heated seats. I'm personally loving the dash design as I didn't care much for the one that was in my LT.

Sorry for wasting everyone's time, but I just had to share...

Not a waste of time at all and thank you. Real world reviews from actual owner/operators uncompensated for their "slanted" views are an asset. Much easier to believe and take stock in someone's word when a company is not paying them to say what they want for advertising purposes.

Glad to hear you like the truck. One of my buddies purchased a similar to yours truck a month ago and says about the same with his experiences. Now he is die hard GM so switching brands was never an issue but he did go with the diesel this time and talks about how quiet and smooth in operation it is.

Hope you continue to enjoy it.

The shifting seems to be spot on in that truck. Seems like it's always where it needs to be. The motor is definitely much quieter than any diesel I've ever owned, which is something I don't really care for...I used to love the purr of that motor heading down the highway towing a load...

Congratulations on the new truck.
You can get tuners for the LML but they are mostly plug and play and you can make the engine louder with an exhaust.

I thought with the DPF it was almost impossible to do an exhaust unless you ran a tuner that removed that from the system? I'd love to do an exhaust and make it a little louder, or a lot...either way, but I don't want to screw with the warranty too bad being I just got the thing last week.

well when i say exhaust, I'm talking about DPF back exhaust. those shouldn't void a warranty, in fact the dealer around here puts them on.

I gotcha. I looked at the DPF back, but doesn't seem that would make it any louder at all so kinda seemed like a waste of money to me.

Just an update though, I finally got to tow with the truck this weekend. Got to tow one of our tractors and a couple other things around the hunting lease. On the way back I towed a trailer with 2 Polaris Ranger 800's with full steel cabs covered in some good ole red clay. All I can say is that this thing tows like a beast...I was really impressed at how effortless it moved around anything I put behind it.

I have an LMM and the studs for the muffler broke, the muffler was rubbing on the drive shaft, that was the only noise I heard, the exhaust is so big it makes no difference at low power with or without the muffler on the LMM anyways.
Congratulations on the new truck!

DPF Back Exhaust will make no difference in sound. Id save the coin put it toward fuel it will change nothing.

Not sure about the dmax but I on the ps and cummins a filter back straight pipe exhaust will make a difference in sound.