To answer the original question, I am running a set of Casserly's 155's in this engine. My mileage is 18.3 empty @ 70mph (up from 17 on the stock injectors). That is on a crewcab 4x4 dually. Towing 14K I am up almost 1mpg over the stockers.
Smaller displacement engines work harder with large tires, but 14 is pretty low for that setup. With a 4" lift, 35" tires, and 4.30 gears, I get 17 mpg running 65mph on the highway. Around town I get 11-12.
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