Fleece Performance Duramax & Cummins Diesel Parts

Fleece Performance Duramax & Cummins Diesel Parts

Fleece Performance Engineering has grown from a small Indiana operation into one of the most respected names in high-performance diesel upgrades, with a product catalog built specifically around the Duramax and Cummins common rail diesel platforms that dominate the high-horsepower diesel community. Founded by brothers Brayden and Chase Fleece in a rural west-central Indiana pole barn, the company established itself as a technology leader in common rail injection systems within five years, developing the Cheetah turbocharger line and the TurboBrake electronic exhaust brake that have become standard references for what diesel performance engineering can achieve. Fleece operates from an 18,750-square-foot Brownsburg, Indiana facility capable of in-house design, manufacturing, assembly, and testing, placing them among the high-output diesel specialists who supply race teams and serious street performance builds. This collection covers Fleece Performance's full range of Duramax and Cummins performance products.

Popular Upgrades

Fleece's Cheetah billet turbocharger upgrades for the LLY, LBZ, LMM, LML, and L5P Duramax engines are among the most sought-after single-turbo solutions in the diesel performance market, providing significant compressor wheel and turbine improvements over the factory Garrett turbocharger while retaining the factory mounting location and piping connections for a clean installation. The Fleece TurboBrake electronic exhaust brake for Duramax applications creates variable exhaust backpressure for engine braking without the heat and brake wear associated with relying solely on foundation brakes when descending grades with heavy trailer loads. Fleece fuel system products including high-flow lift pump kits, CP3 pump upgrades, and dual CP3 conversion kits for extreme horsepower Duramax builds address the fuel delivery limitations that prevent injector command volumes from being met at high power output levels.

Performance and Handling

The Duramax and Cummins common rail injection systems operate at injection pressures above 25,000 PSI, and maintaining correct rail pressure under high-demand fueling requires both an adequate lift pump supply and a high-capacity high-pressure pump capable of sustaining commanded rail pressure across the full rpm and load range. Fleece's CP3 and CP4 replacement and upgrade kits provide verified flow capacity improvements over factory pump specifications, with complete kits including the correct drive gear and timing components for each engine generation. For towing applications, the TurboBrake significantly reduces the thermal load on the factory braking system during extended downhill grades, reducing rotor and pad temperatures and extending service intervals on trucks that spend significant time in mountainous terrain with loaded trailers.

What Duramax engines does Fleece Performance cover?

Fleece Performance has products for every Duramax generation including the LB7 produced from 2001 to 2004, LLY from 2004 to 2005, LBZ from 2006 to 2007, LMM from 2007 to 2010, LML from 2011 to 2016, and the L5P from 2017 onward, with turbocharged upgrade kits, fuel system components, and exhaust products specific to each generation's injection system architecture and turbocharger mounting configuration. The LML and L5P generations with emissions aftertreatment systems including SCR and DEF injection require careful integration of performance parts with existing emissions hardware, and Fleece offers solutions designed to work within or alongside factory aftertreatment for customers maintaining street legal operation. Cummins 5.9 and 6.7 ISB engine coverage includes turbocharger upgrades, fuel system improvements, and injection timing products for both 12-valve mechanical and 24-valve common rail variants.

How does the Fleece Cheetah turbo improve Duramax performance?

The Fleece Cheetah uses a billet aluminum compressor wheel machined to tighter clearances than the cast factory wheel, improving airflow efficiency and reducing compressor wheel inertia for faster spool response under load, with the turbine housing maintained at factory dimensions for a direct replacement installation that does not require exhaust system modification. The Cheetah's larger compressor map compared to the factory Garrett turbocharger supports higher airflow volume for builds that have added significant fueling through tuning and fuel system upgrades, allowing horsepower levels well above factory specification on a single turbocharger rather than requiring a compound turbo system. Fleece provides the Cheetah with their warranty support and technical assistance for proper installation, making it a confidence-inspiring choice for builders who want a manufacturer-backed upgrade rather than an anonymous replacement unit.

Why These Parts Fit Right

Every Fleece Performance product in this collection is cataloged by diesel engine generation and model year, with specific Duramax and Cummins VIN and engine code fitment data to ensure correct turbocharger, fuel system, and electronics compatibility. Installation instructions and torque specifications are provided with each kit for professional and advanced DIY installers. Parts ship fast from stocked inventory to minimize downtime on working trucks and builds.

Complement Fleece diesel upgrades with a matched exhaust system upgrade, improve intake airflow with air intake systems designed for diesel applications, or explore chassis upgrades in the suspension collection to handle the added torque output.