Home » 2011-2015 Chevy/GMC Duramax LML 4" DPF & CAT Delete Pipe (with Muffler)

Compatibility: 2011-2015 Chevrolet / GMC Duramax 6.6L LML

Product: 4" DPF & CAT Delete Pipe System

LEGAL DISCLAIMER & COMPLIANCE

OFF-ROAD USE ONLY: This high-performance racing component is engineered exclusively for competition or sanctioned off-road use. It does not comply with federal or local emissions laws for highway operation. Installation on any vehicle registered for public roads is strictly prohibited. The end-user assumes all legal liability and risk associated with the installation and use of this product.

PHASE 1: DISASSEMBLY & OEM REMOVAL

Step 1: Sensor & Connection Preparation Carefully remove all EGT and pressure sensors from the exhaust tubing. Loosen the primary flange securing the factory downpipe to the DPF/exhaust assembly.

Step 2: DPF Unit Extraction

  1. Disconnect all factory electrical plugs and ventilation lines from the Diesel Particulate Filter (DPF). Secure unused harnesses to the truck frame or remove them from their mounting clips.

  2. Lubricate the exhaust hangers with WD-40 or a silicone-based spray. Pry the hangers from the rubber isolators and remove the factory DPF unit from the vehicle.

Step 3: Primary Downpipe Removal

  1. Clamp Removal: Locate the V-band strap clamp on the turbocharger downpipe. Loosen the bolt sufficiently, then use a flat-head screwdriver to pry the clamp away from the flange at the three contact points.

    • Note: Retain the factory V-band clamp, as it is required for the installation of the new system.

  2. To facilitate easier removal of the stock downpipe, detach the hanger secured to the transmission housing. If the pipe is difficult to extract, cutting the factory pipe inlet may be necessary.

PHASE 2: COMPONENT INSTALLATION

Step 4: Installation of Downpipe #1

  1. Insert the metal hanger on Downpipe #1 into the upper hole of the hanger bracket or OEM rubber isolator.

  2. Install the downpipe using the factory turbo V-band clamp.

  3. Tech Note: Tighten the clamp enough to secure the pipe in place while still allowing for slight movement to facilitate final alignment.

  4. Re-secure the support hanger to the transmission housing using the original bolts.

Step 5: Intermediate Pipe #2 Integration Connect the beveled/sloped end of Pipe #2 to the outlet of Downpipe #1. Secure loosely with a clamp. Simultaneously insert the integrated hangers into the OEM rubber isolators.

Step 6: Muffler Replacement & Wheelbase Adjustment

  1. Connect the Muffler Replacement Pipe (#3) to the first section of the factory over-axle pipe.

  2. Wheelbase Configuration:

    • For EC/SB (Extended Cab / Short Bed) models with a 143-inch wheelbase, you must trim approximately 8 inches off the non-expanded end of Pipe #2.

    • Measure and verify the overall length before performing any cuts to ensure a precise fit.

PHASE 3: FINAL ALIGNMENT & TORQUE

Step 7: Sequential Tightening Perform a final visual inspection to ensure the system clears all chassis components, cables, and heat shields.

  1. Starting at Pipe #1 (Downpipe), tighten the turbo V-band clamp.

  2. Proceed gradually toward the rear of the vehicle, tightening each joint and clamp while verifying adequate clearance at every connection point.

POST-INSTALLATION ADVISORY

  • ECM Tuning: This hardware modification requires a compatible Electronic Calibration (Tune) to disable the factory emissions logic. Without software modification, the vehicle will enter "Limp Mode."

  • Thermal Check: Re-torque all clamps and the turbo V-band hardware after the first 50–100 miles of driving to account for material settling and thermal expansion.