Wehrli 20-24 Chevrolet 6.6L Duramax L5P Stage 3 High Flow Intake Bundle Kit - Illusion Cherry

Wehrli Custom Fab's Stage 3 High Flow Bundle Kit is their most complete airflow upgrade for the 2020-2025 Chevrolet Silverado and GMC Sierra 2500 HD and 3500 HD with the 6.6L L5P Duramax. It combines the full Stage 2 intake system with a 3.5-inch down pipe, addressing airflow restrictions on both the intake and exhaust sides of the turbo in a single package.

On the intake side, a 4-inch aluminum pipe feeds into an enclosed air box with a dry filter and Outerwears pre-filter cover, pulling cold air through the hood ram air duct and inner fender. The intake horn is over an inch larger than the stock unit, and Wehrli reports a 25 HP gain when paired with the 4-inch turbo inlet and a Max Effort tune. Silicone boots with stainless T-bolt clamps replace the factory clip ring design at the Y-bridge connection for a tighter seal under higher boost pressures.

The intercooler pipes tackle two more weak spots. The restricted two-piece, resonator-equipped 2.5-inch factory driver-side hot pipe gets replaced by a one-piece 3-inch aluminum tube. The leak-prone two-piece plastic passenger-side cold pipe gives way to a 3.5-inch piece with CNC machined flanges and double O-ring seals. Both pipes are 14-gauge aluminum with mandrel bends for smooth, consistent flow.

On the exhaust side, the 3.5-inch down pipe replaces the crushed factory unit for improved exhaust flow. It comes black ceramic coated with heat wrap pre-installed for better thermal efficiency. The down pipe connects to the DOC (Diesel Oxidation Catalyst) outlet flange and mates with the OEM exhaust system using the factory 4-bolt connection, with bungs for all OEM sensors. The entire Stage 3 kit bolts on without tuning, retains all factory connection points, and is finished in Illusion Cherry powder coat.