Wehrli Custom Fabrication WCF100775-CSTM High Flow Cast Turbo Intake Horn Custom Finish

The Wehrli Custom Fabrication WCF100775 High Flow Cast Turbo Intake Horn is a precision-engineered, CNC machined cast aluminum upgrade designed to replace the restrictive OEM plastic turbo mouthpiece on the 6.6L Duramax L5P diesel engine. Delivering 27% more airflow than stock and offering 25% greater flow area at the compressor inlet, this intake horn is widely regarded as the largest and highest-flowing turbo inlet available for the L5P platform. The -CSTM suffix denotes a custom powder coat finish selected at time of order.

The horn features a true 4-inch inlet with a smooth-flowing transition into a strategically designed anti-surge face that properly engages the turbo compressor cover for optimized airflow and improved drivability. An included #10 ORB threaded billet aluminum hose barb maintains factory PCV system routing, keeping the build emissions compliant. An O-ring seal at the turbocharger face ensures a secure, leak-free connection.

Key Features:

• Flows 27% better than stock intake horn
• 25% greater flow area than OEM at the compressor inlet
• True 4-inch inlet with smooth, anti-surge transition face
• CNC machined cast aluminum construction for durability and longevity
• Includes #10 ORB threaded billet aluminum hose barb for PCV connection — emissions compliant
• O-ring seal at turbocharger face for a secure, leak-free fit
• Compatible with factory VGT turbo and OEM-style aftermarket drop-in turbochargers with larger compressor wheels
• Works with OEM and aftermarket cold air intake systems
• Bolt-on upgrade — no tuning required
• Custom powder coat finish (CSTM variant)
• Includes mounting hardware and new gasket
• Made in the USA
• 1-year manufacturer warranty

This intake horn replaces GM turbo inlet part numbers 12678756, 19432816, and 12682569, and supersedes WCFab part numbers WCF100721 and WCF100833. Also compatible with the L5D 6.6L Duramax found in 2019–2024 Medium Duty (4500, 5500, 6500) GM trucks. All aluminum construction also produces a more aggressive turbo and engine sound compared to the factory plastic unit.