Ultimate work/tow power system optimizes fuel tuning, airflow, air density, durability & MPG, adding +100 hp, +230 lb-ft of constant-duty power. The cure for airflow restrictions. The stock LLY is riddled with airflow bottlenecks - including the intercooler. PowerPack replaces them with free-flowing components that dramatically increase intake airflow and air density and expel exhaust with virtually no backpressure. Colossal power stays cool, sips fuel. All that improved airflow is then balanced with Banks' advanced CleanTune Technology for 41% more HP and 52% more torque than stock, without adding black smoke. This is load-hauling, hill-flattening constant-duty power that keeps its cool. It'll launch you from 0-60 mph 13 sec. quicker and from 40-60 mph 8 sec. quicker when towing. And thanks to the EconoMind's fuel savings features, you'll get up to 19% more MPG, too. Sweet! The Banks difference? Engineering. Forget mis-matched components. Run away from tuners that can destroy your engine. Everything in PowerPack is engineered to work together to maximize your engine's power, efficiency and durability. PowerPack honors your vehicle by safely living within the limits of your engine and powertrain. Your Duramax will run stronger and live longer! All gains measured at the rear wheels. Products listed do not fit 2006 model-year vehicles. Please call for availability on soon-to-be-released products for '06 LLY & LBZ trucks. Engine differences in 2004 vehicles: Early 2004 vehicles - LB7 engine (8th VIN digit = 1). Late 2004 vehicles - LLY engine (8th VIN digit = 2). Split-dual exhaust applies to single-rear wheel applications only (they do not fit appropriately on duallys). Top system for towing and working. Optimizes airflow, air density, continuous power, durability and MPG. Adds up to +100 hp and +230 lb-ft (rear wheel).