Thanks for the tip, I've been told this already. I know looking cool doesn't get good mileage so I may have to resort to stock suspension and wheels.

do they sell efi live tuned ecm's for lmm? that would be the way to go.... just save the stock ecm for warranty work.

Yep just gota know where to look, duramaxtuner sells them, im sure some of the vendors here do as wel

Thanks guys for your suggestions. Now I just gotta figure out where the money's coming from to make the changes required.

I'd like to thank those of you who took the time to give me suggestions to my mileage problem. I found that by driving with my Allison Transmission in Tow Haul in the city and on the hwy without the trailer that I get better mileage. The only trip I've taken and used this suggestion I got 17 mpg on the freeway instead of 10. The same suggestion for the Tow Haul also mentioned when towing do not use the Tow Haul but run the 6 speed transmission in manual 5 (haven't tried this with my trailer yet so I don't know the out come).

Thanks again everyone

What's the best mileage have had with the lmm by checking at the pump I've been tuning my dads 08 and just built a new tune for it tuesday nite and put it in yesterday morning when he filled up to check the mileage we drove it around yest to a couple jobs and then today most of the miles was country rds running 65-70 and some thur town stop n go's we went 312 mile on only a Lil over a quarter of a tank. So we stop to filled it up and it on took 9 gallons even so I walked by in and asked the cashier to turn the pump back on to make sure it was really full and it only took seventhy something cents it was .171 gallon so on 312 mile it only use 9.171 gallons which equals 34.02 miles to the gallon I couldn't believe it cause I was excited at 21.9 which was what it was showing on the dash. My dad is happy as hell and he don't want to take it out but I'm really happy with this tune.

You people figuring the milage based on miles driven divided by gallons to fill up, or just looking at the display? In my experience the computer is overly optimistic, yours might be ok, probably oughta check if you haven't already.

[QUOTE=rocko cummins;877231]
What mods have you done to that truck?

I bought my truck 2 years ago, it's a 2007 1/2 LMM. To my knowledge the engine is stock. I do have 20 inch rims, approx. 6 in lift kit on it and a cab height camper shell.