2017-2025 Duramax 3.5" Downpipe (L5P-EXH-A004)

Fits

Year	Make	Model
2017-2025	Chevrolet/GMC	Duramax L5P w/ 6.6L

Note: Required custom tuning. For Off-Road and Competition Use Only.

Elevate your L5P’s performance and ditch the bottleneck. The factory L5P downpipe is notoriously restrictive, featuring a "crushed" profile that robs your engine of power and sends EGTs through the roof. The Dirty 3.5" Downpipe is the solution, engineered to provide a smooth, high-flow exhaust path directly from the turbo outlet.

Constructed from full T304 stainless steel, this downpipe is built to handle the intense heat and vibration of a hard-working diesel. It features a precision 4-bolt flange that mates perfectly with the factory turbo and works seamlessly with either the OEM exhaust or any aftermarket race system. To ensure your engine bay stays protected, every kit includes a high-quality heat wrap to keep temperatures under control. 

We highly recommend pairing this with our L5P EGR Upgrade Kit to address factory system weaknesses simultaneously.

Part Number: L5P-EXH-A004

Why Shop Dirty?

• Canadian-Made Performance: High-performing parts made in-house in our shop in West Kelowna and sourced from across North America with the highest quality standards
• Born in the Shop: Our parts are engineered with real-world experience. Whether it's an OEM fix or a performance upgrade, we build what we know works. We make our parts to solve real-world problems.
• Dirty Made Quality: We aren’t just designing the kits; we are installing them every day in our own shop. We use our own products every day. From the first weld to the last bolt, we build tough gear that actually fits, handles abuse, and looks the part.

• Replaces the restrictive "crushed" OE downpipe and catalytic converter for maximum flow.
• Significantly lowers Exhaust Gas Temperatures (EGT) and increases horsepower.
• Full stainless steel construction ensures long-term resistance to corrosion and heat.
• Direct-fit 4-bolt flange connects to the factory turbo outlet without modifications.
• Versatile design works with both OEM and aftermarket race exhaust systems.

• (1) Dirty 3.5" Stainless Steel Downpipe
• (1) High-Quality Exhaust Heat Wrap Kit

Diameter	3.5" (89mm)
Material	T304 Stainless Steel
Connection	4-Bolt Precision Flange

 

We overengineer everything we make. It's manufactured to last and tested to prove it, and if by some strange anomaly it ever lets you down, we'll fix it, have a word with whoever built it, and come back stronger. That's the Dirty Lifetime Warranty. Click here for all the details.