Home » 2017-2025 6.6L Chevy GMC Duramax L5P 4" DPF & CAT Delete Race Pipe

Compatibility: 2017-2025 Chevrolet / GMC Duramax 6.6L L5P

Product: 4" DPF & CAT Delete Race 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 & Flange Disconnection Carefully remove all EGT and pressure sensors from the factory exhaust stream. Loosen the primary flange securing the 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 similar silicone-based lubricant. Pry the hangers from the rubber isolators and remove the factory DPF unit from the chassis.

Step 3: Primary Downpipe Removal

  1. Critical Hardware: Use a 15mm socket to unscrew the 4-bolt flange that connects the OEM turbo direct pipe to the factory downpipe.

    • Note: Do not discard the OEM nuts. These high-strength nuts are required for the installation of the new system.

  2. To facilitate easier removal of the stock downpipe, detach the hanger secured to the transmission and, if necessary, cut the factory pipe inlet.

PHASE 2: COMPONENT INSTALLATION

Step 4: Installation of Downpipe #1 (4-Bolt Flange Connection) Align the 4-bolt flange of the new Downpipe #1 with the turbo direct pipe flange.

  1. Secure using the OEM nuts saved from Step 3.

  2. Tech Note: Press the flange firmly into place while tightening. The connection should be snug enough to support the pipe but loose enough to allow for alignment adjustments.

  3. Re-secure the hanger to the transmission housing.

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

Step 6: Custom Fitment & Pipe #3 Alignment Measure the gap between Pipe #2 and the rear exhaust assembly. Install Pipe #3 into the configuration.

  • Adjustment: If the wheelbase requires a specific fit, measure from the beveled end and trim the pipe to the required length to ensure a seamless connection.

PHASE 3: FINAL ALIGNMENT & TORQUE

Step 7: Sequential Tightening Perform a final inspection of all clearances (chassis, suspension, and heat shields).

  1. Starting from Pipe #1, tighten the turbo V-band clamp/flange bolts.

  2. Proceed gradually toward the rear of the vehicle, tightening each joint and clamp while verifying that the system remains properly aligned.

💡 POST-INSTALLATION ADVISORY

  • ECM Tuning: This hardware modification strictly requires a compatible Electronic Calibration (L5P Unlock/Tune) to disable the factory emissions logic. Without software modification, the vehicle will enter "Limp Mode."

  • Maintenance: Inspect all connection points and the 4-bolt flange hardware after the first 50–100 miles. Re-torque if necessary to account for thermal settling.