The reason we bought the duramax is because it has enough power stock to pull our 35 ft alpenlite.
2001 35 ft avalon alpenlite RK
2005 3500 2wd duramax CC dually
trailair center point suspension
JT Strong Arm Stabilizers
KSH 55 inbed fuel tank
Induction Overhaul Kit
TST tire monitors
EFI-LIVE can increase the timing, which will help mpg's with minimal risk of breaking things, A small 5-10% fuel increase can also be done with minimal risk - the 4-5 and 5-6 shifts are where most people get in trouble.
Don't think I would mess with it.
I had an '03 LB7 and currently have an '07 Classic LBZ.
The difference between the LB7 and the LBZ driving under exactly the same circumstances, driving habits etc. is nearly exactly 2MPG difference.
I run all the time with a big rack and toolboxes, which weighs around 2000 pounds and is as aerodynamic as a brick. So based on that, my '03 LB7 got around 14 MPG, my LBZ gets around 12, not towing.
Towing, I don't see that big of a difference because I am always driving with at least a ton on the back of my truck. Towing, on both trucks, my economy goes south about 15 to 20%.
And yes, my foot is a bit heavy, always has been. I do like the feeling of passing things going up mountain hills towing, with the cruise control on.
The D-max has plenty of power right out of the box. I see no need to chip it unless you want to roast the tires off the line and be the first guy to the next light. I seriously doubt you will see any increase in MPG. It is all relative. More ponies equals more fuel burned under most all circumstances.
2007 GMC 3500 dually ext. cab 4X4 LBZ
Duramax / Allison Fire Red
Total waste of time, money and brain cells IMO. I've chipped two trucks and won't again. Oh but I wanted the towing power, fuel milage and planned to keep the truck forever! Good luck with that decision, really.
a bit of warning. starting with MY 2006, GM can check the ECM to see if a non factory program was ever installed in the truck. even if you remove it, and put back the factory program, the checksum will be stored showing a modified program. can result in a denied warranty claim and a void in power train warranty. In some cases the dealer will need to do the check and send verification to GM showing no modified program was ever installed before they will authorize a warranty power train repair. If your still under your 10 year power train warranty with mileage it's something to consider.
If you go with EFI live, you can buy a new ECM and keep the old ECM with factory programing to swap back in so it doesn't show a non OEM program.
2011 Keystone Outback 295RE
2004 14' bikehauler with full living quarters
2004.5 Silverado 4x4 CC/SB Duramax/Allison
I have a 2006 LBZ and I tow heavier than you and consistently get 12 mpg plus/minus a half or so. I never tow over 60 mph. I wouldn't touch it with any programmer.
I'm getting about the same results for our LBZ and all I do is put the truck in "D", turn on "T/H and set the cruise for a 100 klicks and drive.
my 04.5LLY gives similar mileage. heavy mountains and I'm in the 10 range, dead flat 12+, average is usually slightly less than 12 hand calculated. I'm towing about 9000lbs TT. And usually keep it under 60.