Home » 2011-2015 6.6L GM Duramax LML 4"/5" Downpipe Back DPF Delete Race Pipe

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

Product: 4" & 5" Downpipe-Back DPF Delete Systems

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 factory exhaust tubing. Loosen the primary flange securing the stock 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 to prevent heat damage.

  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 chassis.

Step 3: Primary Downpipe Removal

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

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

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

PHASE 2: COMPONENT INSTALLATION

Step 4: Installation of the Performance Downpipe

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

  2. Align the downpipe with the turbo outlet and secure it using the factory V-band clamp.

  3. Tech Note: Tighten the clamp enough to hold the pipe in position, but allow for slight movement to facilitate alignment of the rest of the system.

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

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

Step 6: Wheelbase Adaptation & Rear Section

  1. Position the Muffler Replacement Pipe (#4) ahead of the Over-Axle Pipe (#6) and Tailpipe (#7).

  2. Select the appropriate Extension Pipe (#5) based on your vehicle's wheelbase configuration.

  3. Custom Fitment: Measure and trim the extension pipe as needed to ensure a precise, professional fit for your specific chassis.

PHASE 3: FINAL ALIGNMENT & TORQUE

Step 7: Sequential Tightening & Clearance Check 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 and professional appearance at every connection point.

POST-INSTALLATION ADVISORY

  • ECM Tuning: This hardware modification strictly 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 the turbo V-band clamp and all pipe clamps after the first 50–100 miles of driving to account for material settling and heat cycles.