High-Flow Up-Pipes (OEM-Length) Optional Downpipe | 2017–2026 L5P Duramax 6.6 (2500HD/3500HD)

OEM-Length Replacement High-Flow Up-Pipes (L5P Duramax)

GM gave the L5P a lot of power from the factory, but the stock up-pipes are a known choke point. The OEM-length replacement high-flow up-pipes are a direct bolt-on upgrade designed to reduce restriction and help the turbo breathe easier—without changing the factory-style layout.

The high-flow design increases exhaust airflow by up to 46% by enlarging the OEM bottleneck area and smoothing out restrictive bends. The result is improved exhaust efficiency, reduced backpressure, and lower EGT potential under load.

Key features

• Up to 46% increased exhaust airflow / larger flow area vs. stock
• OEM-length, direct bolt-on replacement (no custom fab required)
• Heavy-duty stainless construction with internally-sleeved bellows built to handle heat, pressure, and engine movement
• Stainless gaskets included

OEM cross reference

• GM Equivalent P/Ns: 12676611, 12688021

Fitment

• 2017–2024 GM 6.6L Duramax (L5P) up-pipe kit
  Commonly listed for 2500HD / 3500HD Silverado & Sierra applications—confirm by model/year if you’re ordering for a later truck.

What’s included

• Driver + passenger OEM-length high-flow up-pipes
• Stainless gaskets

Notes: Designed to retain factory-style configuration. Always verify fitment before ordering (especially on newer model years and emissions-package variations).