4″ / 5″ Downpipe-Back DPF & CAT Delete Exhaust System – 2020–2025 GM Duramax L5P 6.6L (2500/3500)

Take your 2020–2025 GM Duramax L5P 6.6L to the next level with this downpipe-back DPF/CAT delete exhaust system. Engineered for maximum airflow, aggressive sound, and proven reliability, this system unlocks the performance your Duramax was built for. Say goodbye to factory restrictions and hello to power, efficiency, and a bold exhaust tone.

🔧 What’s Included

• SS409 Downpipe-Back Race Exhaust – built tough for L5P Duramax 2500 & 3500
• Mandrel-Bent Tubing – smooth bends for unrestricted exhaust flow
• Pre-Bent Exhaust Hangers – perfect factory fitment
• 1.25″ Wide Band Clamps – heavy-duty, leak-proof design
• Optional Muffler Upgrade – run it straight-piped or with a muffler
• Polished SS304 Exhaust Tip – 1″ larger diameter for a commanding look
• Reuses factory 4-bolt downpipe hardware

🚙 Vehicle Fitment

• Fits 2020, 2021, 2022, 2023, 2024 & 2025 GM Duramax L5P 2500/3500 6.6L Diesel
• Works with Regular Cab (short & long bed), Crew Cab (short & long bed)
• ❌ Does not fit Cab & Chassis models (4-bolt only)

🛡️ Built to Last – T-409 Stainless Steel

• Made from T-409 stainless steel – tough, rust-resistant, and built for long-term use
• Note: Unlike T-304 stainless, T-409 is magnetic — a magnet will stick, but durability is top-notch
• Best choice for trucks running in salty winter road conditions

⚡ Performance Gains You’ll Notice

• Deletes DPF & CAT restrictions → better exhaust flow, lower EGTs, and more power
• Aggressive diesel sound that turns heads
• Fuel efficiency boost → up to 18–19 MPG combined (driving habits & tires affect results)
• Improved throttle response & pulling power → ideal for towing or daily driving

⏱️ Easy Installation

• Install time: ~1 hour with basic hand tools in your driveway
• Faster with a lift
• Cutting may be needed for certain short wheelbase configurations
• Kit includes all clamps, hangers & hardware (reuse some factory components)

💻 Tuning Required

This system requires specialized race tuning to prevent check engine lights and optimize performance.

• We recommend EZ Lynk AutoAgent 3 for L5P Duramax trucks
• Check our tuning section for compatible solutions

✅ Why Choose This Exhaust System?

• Perfect fit for 2020–2025 GM Duramax L5P 2500/3500
• Built with high-strength stainless steel for durability
• Aggressive sound + real-world performance gains
• Easy install with full kit included
• Backed by the reliability serious Duramax owners demand

🔥 Unleash your L5P’s true potential with this 4″ / 5″ Downpipe-Back DPF & CAT Delete Exhaust System. More power, more sound, better efficiency — built for drivers who demand performance.