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I have heard from different people that the engines are de-tuned so-to-speak and after so many miles you will notice a mileage increase and a horse power gain once the break-in period is complete. Has anyone noticed this with there truck and how many miles did you have on it if so? I am getting 14/15 MPG now driving around "city" but half of the problem is me having that much HP at my dispense.
 

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It will get better after around 10-15k. My LMM hit the 10k mark and my mileage picked up a little. My LMM is a special case because it has a utility box on it and weighs almost 11k. The biggest bang for my buck was to delete the DPF, it picked up a solid 3 mpg. If you have a new 2011 deleting the DPF/Urea will get you better economy but you will also lose your warranty.
 

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I also heard the same thing but didn't notice anything and I just hit 35k. but I deleeted my DPF and had the Stealth II since about 8k. Doing the I picked up about 3mpg around town and 4-5mpg highway. So I am not sure if I got the mpg bump after so many molesbut I have heard many time from many people it does. So I just figured mine happened about the same time I got rid of the DPF.
 

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I have abuot 5400 miles on mine - have not seen any change
 

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Mine seems to still be improving - at about 14,000miles now.
 
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