2017-2019 L5P Duramax Stage 3 High Flow Intake Bundle Kit

Stage 3: more air, fewer weak points

Wehrli's Stage 3 kit for the 2017-2019 L5P packages its Stage 2 high-flow bundle plus its 3.5 in. downpipe together, aimed at the weak points in the factory air path that can lead to boost leaks and lost power.

On the intake side, a 4 in. fabricated aluminum pipe, an inlet horn more than an inch larger than stock, and a 10 ga aluminum air box replace the plastic factory parts, drawing cooler air in through the ram-air duct in the hood and the inner fender. Wehrli measured a 25 hp gain from the 4 in. inlet with a max-effort tune.

After the turbo, the two-piece resonator-equipped 2.5 in. hot side pipe and the plastic-and-rubber cold side pipe are replaced by one-piece 3 in. and 3.5 in. 14 ga aluminum pipes. The cold side uses a CNC-machined flange with double O-rings and a silicone boot in place of the factory clip ring.

The 3.5 in. downpipe replaces the crimped factory pipe. It is ceramic coated and heat wrapped, bolts between the DOC outlet and the factory 4-bolt front pipe flange, and keeps the factory sensor bungs.

Who it's for

2017-2019 L5P owners who want a bolt-on airflow upgrade that also fixes the factory leak points.

Key specs (per Wehrli)

What's included

• Aluminum intake tube, 4 in.
• Inlet horn, 4 in., with surge ring and PCV fitting
• Air box, dry filter and pre-filter
• Intercooler pipes: 3 in. hot side, 3.5 in. cold side
• Machined cold side flange with twin O-rings
• 3.5 in. downpipe with sensor bungs
• Boots (silicone), clamps (stainless T-bolt) and hardware; powder-coated finish

Fitment notes

• Fits 2017-2019 Chevrolet Silverado / GMC Sierra 2500 HD and 3500 HD with the 6.6L L5P Duramax.
• Wehrli says the kit pairs best with compliant tuning and an upgraded drop-in turbo.
• California: Wehrli does not ship this part to California.

Professional install available at Powertech Diesel, Idaho Falls — call 208-542-7793.