I bought a 2010 2500 with the 6.0 this year. To put it lightly i am NOT impressed with the gas mileage. My average is 12mpg which is about wat my 93 ford 460 gets! My local performance shop says the 6.0 is a lost cause as far as performance upgrades go and that i should just buy another duramax or live with wat ive got. But i have a hard time justifying paying another 10 thousand dollars when i dont pull daily. Does anyone have any experience with the new 6.0s as far as getting more power and mileage out of them?

 

Ive read about a diablo programmer? Has anyone been around one?

 

I had one on my '99 Sierra with the 5.3L... I saw a very, very slight mileage increase (15.8 up to 16.0 on Hwy), but only at the expense of running premium fuel, and no seat-of-the-pants power increase.
The biggest difference was increased shift firmness. I would not buy it again. I did like being able to adjust the speedo for different size tires tho.

I bought a 2009 Silv 1500, with the Max trailering package, 6.0L, 6spd, 3.73, and instead this time I bought into HPTuners. LOTS more parameters to mess with, much more powerful tool. Ask around on their forum for someone in your area if you want, they can license multiple vehicles, and many people are happy to help out.

Dan

 

I have an '09 Chevy 1500 4x4 Ext Cab with the L76 (called Vortec Max in previous yrs) w/Active Fuel Mgt, MYC 6-Speed Tranny, GU6 3.42 RA, G80 Auto Locking Diff, Z60 Performance Suspension, GM 20" Rims w/Goodyear Eagle LS2 A/S P275/55R20s (Nitrogen filled at 33psi). Adds are a Magnaflow Catback Dual Exhaust,GM Bedrug and a Leer R100 Flush Mounted Topper. The sticker quoted the EPA Fuel Ecomony Estimates at 13 City and 18 Highway. The best I've ever seen is 12.4 City and 16.5 Highway. I drive, in most cases, the speed limit. It will run like a raped chicken but, the mileage sucks, IMO. I've recently moved from Denver to Pensacola and really expected a change....BUT No, No, No! Love my Chevy, though!

 

Give that baby time to warm up man! That's all it needs.

But, EPA estimates are usually generous at the least.