I noticed the biggest mpg improvement by increasing air flow to the intake. I don't want to rub it in but I'm getting 20 to 22 mpg hand calculated. I don't have a programmer yet...
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06 2500 QCSB SRW G56, B&W, 4" factory pipe no muffler or resonator, custom cold air, 100% AMS oil with nano filter, quadzilla commander and Smarty.