Harper220

I've got the 2004 Duramax 6.6 turbo diesel and I've talked to a few guys that said they were getting 22-24 mpg. One said something about Bullydog and can't remember the other. To make this easy, I don't believe it!! Best I ever got was 17-18 mpg, but usually average 16 mpg. I have the Hypertech programmer, great power gains for the money, but no where near 22-24 mpg. Am I missing something??

GLH

Change your air-filter

Madmax

Nope, it's all BS. Any possible gains made by the programmer will be outweighed by your suddenly heavy right foot..

Seriously tho, I can get 20 mpg on the highway at 65mph, and 16-17ish combined driving. That's about as good as they get. I've got the predator programmer, Boost stick, Cat removed, egr blocked, and a cold air intake.

The programmers throw the computer mileage calculator on your dash waaaaay off, and that's where most people think they are getting better mileage. Checking it by hand will confirm the ugly truth....

Jupiter Sunsation

Got a 03 Crew Cab DD 2wd and the best I have ever gotten was 18 mpg. I am convinced that the typical owner cannot do simple math and really believes that a 300 HP truck that weighs over 3 tons and punches a 48 sq ft hole in the wind gets 25 mpg! Simple math folks, 20 gallons to get it back to full and 360 miles travelled is 18 MILES PER GALLON!

Harper220

I did... I bought the "Green" filter. Suppose to be the best out there.

PMTCHIPS

2004 LB7 or LLY??

www.pmtdiesel.com

DOUBLE J

I have 2002 3500 duramax, i've been getting 20-23 mpg on intersate running 80-85mph, no BS. I would'nt have beleived it myself. I have the quadzilla programmer that will take it up to 215 extra hp, airraid intake, 4inch exhaust. I have got it set on 165hp, dont wont to go to high without doing some tranny work. This chip also calibrates speedomter with your tire size, and takes off the top end limiter. Not only did it improve gas mileage its fun as hell to pull up beside a mustang and drill it in a 8000# truck. I would recommend this programmer anyday.

44MTI

I have a 03, 4 wheel drive that I average 19 and I drive 80-85 most times. When my friend pulled my 42 cat to florida he got 17, then drove from for St Louis to tulsa and averaged 21. I would not have believed it either but there were two trucks and 4 guys who all ckecked it.
I have the bully dog programer, Intake and 4" cat back exhaust. I think you have to have all three because while I was waiting on the exhaust, about 2 wks with the other mods, It didn't get as good or run near as good. Also I do have a hard bed cover.

JPD Motorsports

2003 cc dually 2wd lowered down with the mac airfilter 5"exhaust kit aero turbine muffler running the quadzilla tune at 190hp setting going to florida running a constant cruise setting at 77mph I got between 21 and 23 the whole way there and back with the truck loaded with gear, no trailer and a hard be cover on it, this is hand calculated no dic numbers.

NJSONIC

2002 K3500 crew cab with the allison trans.-the best I've gotten has been 19 mpg on the highway light load and driving 65 mph. The truck is stock. It looks like you can get in the 20 mpg range if you have a two wheel drive.