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700hp LBZ Duramax Daily Driver

Fit For the Street— At Home in the Dirt

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Owning a Duramax brings with it an inherent potential to easily add more horsepower. For most, it begins with an off-the-shelf programmer, or a tune created using EFILive. Then, once the rush of 500 rear-wheel ponies turns the owner into a full-blown enthusiast, he often finds himself in a game of chess—always looking to make his next power move. Justin Koger got started with a simple EFILive tune, and his life has never been the same since.

As a rural Indiana resident, Justin is surrounded by the diesel pickup culture, and he knew right from the get-go that a simple tune wouldn’t be enough to keep up with the locals. So after a few trips over to Fleece Performance, which had initially turned up his ’06 LBZ, he found himself behind the wheel of not only a 700hp street truck, but a competitive sled puller as well.

In order to meet local Work Stock Class sled pulling rules, a turbocharger with an inducer 2.5 inches (63.5 mm) in diameter (or smaller) had to feed the engine. So an S300-based unit with a 63mm compressor wheel inducer was installed. The Cheetah S363 (as it’s called) features a non-wastegated turbine housing, but the turbine wheel has an exducer that measures 73 mm. The large 73mm turbine wheel (in relation to the 63mm compressor wheel) helps keep drive pressure reasonable. A 4-inch turbo-back exhaust feeds into a Silverline 6-inch, miter-cut stack in the bed for a quick exhaust gas exit.

Taking care of fuel delivery is a 165-gph AirDog II fuel system, which feeds an Industrial Injection Dragon Fire CP3. The modified CP3 is said to flow 85 percent more fuel than the stock injection pump. The injector nozzles were upgraded with units that flow 60 percent more fuel than stock. Other than the nozzle swap, the only internal engine modification has been the addition of a set of ARP head studs.

The six-speed Allison 1000 was beefed up courtesy of Sun Coast’s GMax 6-pac, which comes with upgraded clutches (C1 through C4), steels, pressure plates, and apply pistons. A Sun Coast 1058 torque converter was chosen to send everything through the reinforced transmission and has proven to be a good match for the high-horsepower tuning and 63mm turbo. Prepping the Chevy’s independent front suspension for pulling called for a set of Fleece Performance’s tie-rod sleeves, followed by Cognito Motorsports’ pitman and idler arm braces.

As the 2.5-inch Work Stock Class continues to pick up steam in his area, Justin is getting more and more into it. According to him, the addiction to pulling happened instantly. “It’s funny. I started with a little EFILive tune and wanted to do some pulling,” he told us. “Then I wanted more power and all the bells and whistles in order to pull and be competitive. Now my family and I go to as many Work Stock hooks as we can.”

As hooked to pulling as Justin has become, he’s only getting started. Plans for a bulletproof engine build are already in the works, along with more fuel and air modifications. Look for this burgundy Silverado to continue to mix it up in Midwest Work Stock Classes for now, but look for it to be the truck to beat in the future.

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