Product Description
The WEHRLI CUSTOM FAB WCF10091 2004.5-2005 LLY DURAMAX 4" INTAKE KIT WITH AIR BOX is a premium airflow upgrade designed specifically for the restrictive factory intake system found on LLY Duramax trucks. Featuring a large diameter 4-inch fabricated aluminum intake tube paired with a sealed air box and high-flow dry filter, this system allows your 6.6L Duramax engine to breathe more efficiently while improving turbo spool and throttle response.
The factory intake system on the LLY Duramax is known for airflow limitations under load. Wehrli Custom Fab engineered the WCF10091 intake kit to deliver smoother airflow, improved intake efficiency, and a durable fabricated design that outperforms the factory plastic intake components. The result is improved drivability, better airflow to the turbocharger, and a clean performance appearance under the hood.
This kit is designed as a true bolt-on upgrade requiring no tuning and includes all hardware necessary for installation. The fabricated aluminum air box protects the filter while drawing cooler air from the inner fender area, helping maintain consistent airflow during towing, daily driving, or performance applications.
Key Features:
- High-flow 4-inch aluminum intake piping
- Fabricated aluminum sealed air box with lid
- Improves airflow to the turbocharger
- Helps increase throttle response and turbo spool
- High-flow dry air filter system
- Includes silicone boot, O-ring seal, and stainless T-bolt clamps
- Direct bolt-on installation
- Designed and manufactured in the USA
Fitment:
- 2004.5 Chevrolet Silverado 2500HD 6.6L Duramax LLY
- 2004.5 Chevrolet Silverado 3500 6.6L Duramax LLY
- 2005 Chevrolet Silverado 2500HD 6.6L Duramax LLY
- 2005 Chevrolet Silverado 3500 6.6L Duramax LLY
- 2004.5 GMC Sierra 2500HD 6.6L Duramax LLY
- 2004.5 GMC Sierra 3500 6.6L Duramax LLY
- 2005 GMC Sierra 2500HD 6.6L Duramax LLY
- 2005 GMC Sierra 3500 6.6L Duramax LLY
What’s Included:
- 4-inch fabricated aluminum intake tube
- Fabricated aluminum air box with lid
- High-flow dry air filter
- Silicone coupler boot
- O-ring seal
- Stainless steel T-bolt clamps
- Installation hardware
FAQ
Will this intake fit LB7 or LBZ Duramax trucks?
No. The WCF10091 intake kit is designed specifically for the 2004.5–2005 LLY Duramax engine. It will not fit LB7 or later LBZ/LMM trucks.
Do I need tuning after installing this intake?
No tuning is required. The intake is designed as a bolt-on upgrade and can be installed on stock or modified trucks.
Does the intake pull cooler air than the factory system?
Yes. The enclosed air box draws air from the inner fender area and shields the filter from engine bay heat.
Will this improve performance?
Improved airflow can help increase turbo response, airflow efficiency, and engine breathing, particularly on trucks with additional performance modifications.
Is this product legal for sale in California?
This product is typically listed as not available for shipment to California. Please verify emissions compliance before ordering.
| Brand | WEHRLI CUSTOM FAB |
| Part Number | WCF10091 |
| UPC | Not publicly listed |
| GTIN | Not publicly listed |
| Shipping Info | Estimated shipping box size 16 × 16 × 24 inches. Typical fulfillment 3-5 business days depending on powder coat option. |
| Construction | 4-inch fabricated aluminum intake tube with fabricated aluminum air box |
| Filter Type | High-flow dry air filter |
| Installation | Direct bolt-on installation |
| Country of Origin | United States |
| Prop 65 | WARNING: Cancer and Reproductive Harm – www.P65Warnings.ca.gov |
