Josh Tillery’s 2018 GMC Duramax L5P Denali 4×4 dually is a genuine workhorse, pulling more than 35,000 lbs on a daily basis. Whether it’s the 44’ trailer hauling a load of baled hay or both of his 4×4 cab tractors loaders with cutters, the Denali gets a chance to frequently flex its muscles. The silver GMC replaced his old ’09 Cummins-equipped Ram, which quite simply was never up to the task of hauling the same type of heavy loads even with an intake and a tune.
“The old Cummins was sitting on overloaded springs and would just bottom out and struggle with the weight,” explains the Hempstead, Texas rancher. “I always had problems with either the suspension or the transmission, and the thing bounced me around like I was piloting a Sherman tank.” Josh continues, “This Duramax tows like a dream, and is so much more comfortable than that old thing.”
Banks Ram-Air cold air intake, Derringer tuner and pillar-mounted iDash DataMonster about six months ago, and he couldn’t be happier. “The additional power makes an already great truck more enjoyable,” says Josh. “You can feel the difference between stock and the Derringer. She tows like there’s nothing behind her. I’ve got plenty of torque to help out with the heavy loads.” Josh also points out that he notices that the truck, even with a 35,000 lb load, it gets up to speed quickly and with little effort. Since the Derringer has built-in watchdog circuitry for monitoring the transmission and engine, it makes for an ideal companion to a truck that works so hard. Josh had researched other tuners and decided on the Derringer after learning about its safeguards like trans slip detection and exhaust gas temperature monitoring.
But towing giant bales of hay isn’t all that the Duramax is tasked with. Every so often he tows his 36’ toy hauler camper loaded with toys like his beautiful cherry red Harley Bagger. The Denali isn’t complaining though, and with the added power neither is Josh.