Wehrli 100373 Billet Exhaust Manifolds | 2017-2025 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax L5P

Features:

• High-flow billet steel construction
• Finished in black ceramic coating
• Fully TIG welded for long-term durability
• Gasket-matched exhaust ports for better flow
• Improves turbo spool and lowers EGTs
• Compatible with OEM and ported heads
• Works with OEM-style up pipes
• 1/8 NPT port for sensors included
• Includes ARP 12PT fasteners
• No tuning required after install
• Compatible with 2019+ L5D medium duty

High-Quality Exhaust Manifold Upgrade for Medium-Duty Duramax

If you're looking to squeeze more power and efficiency out of your L5P Duramax without diving into complicated tuning or custom fabrication, Wehrli’s Billet Exhaust Manifolds are a serious upgrade worth considering. These aren’t your average cast iron replacements—they're fully TIG-welded and CNC-machined from billet steel, built with performance and durability in mind right from the start. The design is gasket-matched at the exhaust ports and internally divided, so you're getting smooth, optimized flow whether you're running stock or ported cylinder heads. That means better turbo spool-up, lower EGTs, and a noticeable improvement in throttle response—especially if you pair them with Wehrli’s 2-inch stainless high-flow up pipes.

Premium Construction & Design

What really sets these manifolds apart is their build quality. They're finished in a sleek black ceramic coating that's rated up to 1800°F, which not only looks clean under the hood but also helps manage heat over time. Wehrli even includes everything you need for a clean install—new gaskets, ARP 12-point fasteners, washers, and assembly lube. There's also a 1/8" NPT port pre-threaded into the driver-side manifold, giving you an easy option to add an EGT or drive pressure sensor. These manifolds are desgined as direct replacements, so they work with OEM-style up pipes and require no tuning after installation. They’re also compatible with 2019+ L5D Duramax medium-duty trucks, so if you’re running a 4500/5500/6500 chassis, you’re covered.

Fits: 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025 GM 6.6L Duramax