4″ GM Duramax L5P Chevrolet Silverado and GMC Sierra Down-pipe Back Race Exhaust System (2017-2025)

This is a 4″ downpipe-back race exhaust system designed for 2017-2025 Chevrolet Silverado & GMC Sierra 2500/3500HD trucks equipped with the 6.6L Duramax L5P engine. Here’s everything you need to know:

Key Features & Fitment

✅ Fits:

• 2017-2025 Chevy Silverado & GMC Sierra 2500/3500HD (pickups only – no Cab & Chassis)

• Engine Compatibility: L5P Duramax (2017-2025)

✅ 4″ Diameter Piping – Improves exhaust flow over stock for better turbo response and performance.
✅ Deletes Catalytic Converter & DPF – For off-road/racing use only (not street legal in the U.S. or Canada).
✅ Bolt-On Direct Fit – Uses factory hangers; includes all necessary hardware (gaskets, clamps, etc.).
✅ Full Downpipe-Back System – Replaces everything from the turbo outlet to the tailpipe.

Performance & Sound

• Reduced Backpressure – Helps lower EGTs (exhaust gas temps) and improves turbo spool.

• Aggressive Sound – Expect a deep diesel tone with noticeable turbo whistle (minimal muffling for a “race” setup).

• Potential Power Gains – Works best when paired with a DPF/DEF delete tune.

Installation Notes

🔧 Bolt-On Design – Should be straightforward with basic tools.
🔧 Lifting the Truck Recommended – For easier access to stock exhaust components.
⚠️ Tuning Required – The L5P will immediately trigger check engine lights and derate powerwithout a proper DPF/DEF delete tune.

Legal & Emissions Warning

🚨 Off-Road Use Only – Removing emissions equipment (DPF/DEF/catalytic converter) is illegal for on-road use under U.S. federal law (EPA) and Canadian regulations.
🚨 Strict Emissions Testing – Many states (CA, NY, CO, etc.) enforce diesel emissions inspections—this exhaust will fail.
🚨 Potential Fines – Heavy penalties apply for tampering with emissions systems.

Required Supporting Mods

• DPF/DEF Delete Tune (MUST HAVE) – Companies like MM3 Tuners (EcoFlash), PPEI, or Duramaxtuner offer L5P-compatible tunes.

• EGR Block-Off Kit (Recommended) – Prevents soot buildup in the intake.

• Boost/EGT/Trans Temp Gauges (Recommended) – Critical for monitoring engine health with performance tunes.

Final Verdict

This is a high-performance exhaust for the L5P, ideal for:

• Drag racing / sled pulling

• Off-road / competition use

• Heavy towing (with proper tuning)

If you need a street-legal option, look for a DPF-back system that retains emissions compliance.

Would you like recommendations for L5P tuners or other performance upgrades to pair with this exhaust?