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lly mileage help

  1. 04.5-05 LLY Performance Parts Discussion
    I need some input for my lly to improve my mileage. Your recommendation are appreciated. Here is the specs and upgrades that I have done thus far on my truck. Please remember as you reply that I'm not into racing and any modifications that I preform will be to improve mileage only. My truck has...
  2. 04.5-05 LLY Duramax Powertrain
    I have an 05 lly and im getting about 12-14 hwy empty and towing really doesn't matter. Why am i getting such horrible mileage?