2017-2026 L5P Duramax Billet Exhaust Manifolds

Factory L5P cast manifolds remain a heat, crack, and flow bottleneck once mileage and load stack up. Wehrli’s billet set replaces both banks with TIG-welded, high-flow billet steel manifolds — exhaust-port gasket-matched, internally divided, and built with an EGR riser flange — for cleaner flow, quicker spool, and lower EGTs without requiring a tune.

This kit (WCF100373): 2017–2026 L5P Duramax billet exhaust manifold kit finished in black ceramic coat (1800°F). Includes new manifold-to-head, EGR flange, and manifold-to-up-pipe gaskets; ARP 12-point head fasteners with washers and assembly lube; plus a driver-side 1/8" NPT sensor port (and plug) for EGT or drive pressure. Outlet geometry stays OEM-style so you can run factory up pipes now and step up to WCFab 2" stainless high-flow up pipes WCF100624 later. Up-pipe fastener kits are sold separately as WCF100199.

Fitment gates:

• Fits 2017–2026 Chevrolet / GMC 6.6L L5P Duramax
• Also compatible with 2019+ L5D Duramax medium-duty trucks (4500 / 5500 / 6500)
• Parent/base manifold kit only — not a complete manifold + up-pipe combo (see year-banded kits with WCF100624)
• Up-pipe fastener kits sold separately as WCF100199
• SEMA Certified emissions-compliant design (SC-WCF01-0174) — keep required emissions equipment where legally required
• Idaho Falls install help available when bay time allows

Shipping: This product cannot ship to California (same restriction as WCFab). Ships in its own box. Free ground over $150 excludes HI/AK.

Call 208-542-7793 with year, L5P vs L5D, and whether you already have (or want) WCFab 2" stainless up pipes WCF100624.

Emissions-compliant performance only — Powertech Diesel does not sell deletes or defeat devices. Keep required emissions equipment where legally required.