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I have an 03 GMC 4x4. Thus far I have been dissapointed with fuel economy. I am getting close to 100K and have been averaging about 16 mpg with mixed driving. I drive like a grandma, maintain my truck well, proper air pressure, etc. Most of the miles I drive the truck is empty. When I tow, I am lucky to see 11 mpg. I log all my miles and have verified by hand, although the computer in the truck is very accurate.

I installed the AFE Stage II filter & intake. Saw an increase in fuel economy of .8 mpg ( 15.4 mpg to 16.2 mpg averaged averaged over 30K).

I am considering new Flex-a-lite fan, 4" exhaust and possibly edge or other type of programmer. Anyone out there have any experience good or bad?
 

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Keeping the fuel filter changed will help some. Most upgrades are for improved power and running cooler. Spending hundreds of dollars to save money on fuel seems counter-productive to me.
The 4" exhaust may help both power and mileage, but only if the turbo-back is used. The smallest restriction limits the entire flow for the piping; like the left side exhaust manifold restriction situation. To demonstrate what this means, next time you wash your truck just turn the faucet on 1/4 turn and try to spray the soap off.
 

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Wow! I am getting 20mpg with mine, all stock! 94000 mile on her. I keep the fuel filter changed and run some additive through it once a month. best of luck!
 

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04 LB7 80,000 mi. 16 mixed, .....18 highway (75mph Ny to Fla.)
 

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Any ideas on how to open up the air filter and get a little more air flow?
I think that should be good for one more mpg. Maybe a little more power to.
 

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Banks makes that ram air intake.
:drink
yea but it's made by s&b lol.

i would do some sort of intake, i'm running an Airaid and it works for me. also some sort of tuner/chip.
 

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I have a 2008 2500HD crew cab Duramax and only get 15.2. It doesn't have a lift or over size tires. I was hoping someone would have an idea of how to get better mileage ? Thanks, Ricky
 

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Hey dirtimaxdougie, do you think your technicooler was worth the money? Looking to get one seeing as how i can hit 1700+ egt on my 1/4.
 

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I have a 2008 2500HD crew cab Duramax and only get 15.2. It doesn't have a lift or over size tires. I was hoping someone would have an idea of how to get better mileage ? Thanks, Ricky
Ditch the DPF and get EFILive. You will lose your warranty if you do though.
 

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Hey dirtimaxdougie, do you think your technicooler was worth the money? Looking to get one seeing as how i can hit 1700+ egt on my 1/4.
Sorry Jake I didn't have an EGT gauge hooked up when I bought the intercooler so I'm not sure how much it dropped. I threw it in as a precautionary measure after I detonated my supercharged 3800 (made me think of my truck blowing too).

I did notice the dmax running smoother but made the intake a lot louder
 

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Hah wow you guys are lucky. I mean I let my truck Idle in the morning for about 15 minutes but I can't see by doing that only getting 9.8 MPG. Previous owner to my 08 2500 HD ext cab Duramax installed an edge power tuner but something doesn't seem right. There's 83,000 miles on it, which only just under 3,000 are since I've had it. My dash computer already called for 2 oil changes, and 2 fuel filters (which I did). 4" MBRP exhaust straight through and dumped just passed the beginning of the bed. I'm In some serious help to improve my MPGs
 

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Not sure what else to say, but every little thing does help. EFI live goes a long way, too. I filled up today and hand calc'd 20.5 on a mostly highway tank. Mods are in my sig.
 
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