Exhaust Manifold with Catalytic Converter for GMC Canyon (2004-2006) 2.8L

Direct-Fit Replacement Exhaust Manifold with Catalytic Converter for 2004-2006 GMC Canyon (GMT355)

What it Does: The integrated exhaust manifold and catalytic converter replaces cracked factory exhaust runners and degraded catalyst substrates on the 2004-2006 Canyon to eliminate exhaust leaks, restore accurate O2 sensor feedback, and silence cold-start valvetrain ticking.

The Stock GMC Canyon Exhaust Manifold Cracking Problem

The factory cast iron manifold on the GMT355 chassis frequently succumbs to extreme thermal cycling and uneven expansion between the cylinder head and the catalytic assembly. Over time, hair-line fractures propagate across the exhaust runner junctions, causing high-frequency ticking on cold starts that partially subsides as the metal expands. More critically, unmetered atmospheric oxygen enters upstream of the pre-cat oxygen sensor through these fractures, skewing fuel trim data, causing rich/lean diagnostic trouble codes (DTCs), raw exhaust smell in the cabin, and reduced low-end torque.

The Engineering Solution

This direct-fit replacement combines a precision-machined tubular stainless steel manifold with an integrated, EPA-compliant high-flow ceramic substrate catalytic converter. Stainless steel construction tolerates rapid thermal expansion without fatigue cracking, while uniform wall thickness stabilizes heat distribution across all primary runners. The assembly matches factory port geometries and OE mounting flanges exactly, eliminating the need for cutting or welding. By restoring an airtight seal and standard backpressure dynamics, it recovers lost cylinder scavenge efficiency and maintains consistent air-fuel ratios without triggering check engine lights.

What's Included

• 1 Exhaust Manifold with Integrated Catalytic Converter
• Exhaust Manifold Gasket
• Downpipe Flange Gasket
• Mounting Studs and Nuts

Technical Specifications

Compatibility

• 2004 GMC Canyon Base / SL / SLE 2.8L L4
• 2005 GMC Canyon Base / SL / SLE / Z71 / Z85 2.8L L4
• 2006 GMC Canyon SL / SLE / WT / Z71 / Z85 2.8L L4

Frequently Asked Questions & Fitment Warnings

Does this fit the GMT355 Canyon?

Yes, this is a direct fit for the 2004-2006 GMC Canyon equipped with the Atlas LK5 2.8L engine. Non-CARB compliant: Not legal for sale or use in California, Colorado, New York, or Maine.

What are the proper installation torque sequences for this assembly?

Clean the cylinder head thoroughly, torque fasteners progressively from the center outward to factory specifications, and re-torque all hardware following the initial heat cycle.

The GMC Heavy-Duty Caliber

Engineered to handle sustained payload hauling and high thermal loads, this stainless steel assembly delivers durable reliability and structural integrity for hard-working midsize trucks.