turbovanman
I has boost, :O)
My brother just bought a 09 3500 PU, 4x4, 4 door, full load and its getting around 12 mpg combined. I saw the other thread so some are around this, some are higher. What can we do to it without voiding the warranty, IE air filter housing, cat back, or an inline programmer as we can't tamper with the stock computer, etc.