Is a 3.5" downpipe too large for a stock turbo L5P?

No. The L5P platform moves a massive volume of air compared to older Duramax engines. Moving from the restrictive factory pipe to a 3.5" diameter reduces backpressure significantly without sacrificing low-end torque, making it ideal for both stock and modified turbos.

Why is the heat wrap not pre-installed on this model?

L5P engine bays are notoriously tight. We provide the Basalt Heat Wrap separately so that during installation, you or your technician can prioritize wrapping the specific sections closest to sensitive wire harnesses or AC lines for maximum localized protection.

Does this pipe include a bung for the EGT sensor?

This is a Competition Series Catless Downpipe. Depending on your tuning setup, it is designed to provide maximum flow. Most L5P delete tunes recalibrate or eliminate the need for factory downpipe sensors, but the smooth surface allows for custom bungs if required by your specific tuner.

Will this fit the newer 2024-2025 L5P models with updated emissions?

Yes. We have precision-engineered the flange and bend geometry to fit the 2017 through 2025 model years. As long as the vehicle uses the L5P 6.6L V8 platform, this pipe will bolt directly to the turbocharger outlet.

What kind of sound change should I expect?

By removing the restrictive factory catalytic converter section and increasing to 3.5", you will gain a much deeper, more aggressive "V8 Diesel Rumble" and significantly more pronounced turbo whistle.

3.5" Catless Downpipe For 2017-2025 Duramax L5P 6.6L V8 | Vigor Diesel

Name: 3.5" Catless Downpipe For 2017-2025 Duramax L5P 6.6L V8 | Vigor Diesel
Brand: Vigor Diesel
SKU: 3494EMD0165US
Price: 218.99 USD
Availability: InStock

SKU: 3494EMD0165US

Quantity

Brand

Vigor Diesel

Pipe Diameter

3.5 inch

Fitment

2017-2025 GMC Sierra 3500 HD 6.6L V8

Material

Stainless Steel

Condition

100% New

Surface

Mirror Polish

Ultra-Flow 3.5-Inch Diameter: Specifically engineered for the high-output L5P platform, the 3.5" oversized tubing offers superior exhaust scavenging compared to standard 3" pipes.
Premium T304 Construction: Built from heavy-duty T304 stainless steel with precision mandrel bends, ensuring zero restriction and maximum durability against heat and corrosion.
Customizable Thermal Protection: Includes high-grade basalt fiber wrap and locking ties, allowing for targeted heat shielding to protect sensitive L5P engine bay components.
Precision L5P Turbo Flange: Features a laser-cut, heavy-duty flange with pre-installed studs for a perfect, leak-free seal directly to the factory or aftermarket turbocharger.

L5P High-Performance Package Contents

1 x 3.5-Inch Competition Series Downpipe (High-Grade T304 Stainless Steel)
1 x Roll of High-Temp Basalt Fiber Heat Wrap (Titanium Finish)
2 x Stainless Steel Locking Ties (For customized heat wrap installation)
Pre-Installed Heavy-Duty Exhaust Studs (Specific to L5P Turbo Flange)

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3.5" Catless Downpipe For 2017-2025 Duramax L5P 6.6L V8 | Vigor Diesel

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L5P High-Performance Package Contents

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