Product Description
Wehrli WCF100120 3" Down Pipe for 2004.5-2010 LLY/LBZ/LMM Duramax
The WEHRLI WCF100120 3" Down Pipe is a direct-fit upgrade for 2004.5-2010 Chevrolet and GMC 6.6L LLY/LBZ/LMM Duramax trucks. It replaces the restrictive crushed factory turbo down pipe / exhaust front pipe with a full 3" steel assembly that is high temp ceramic coated and heat wrapped to keep exhaust energy in the flow path and heat out of the engine bay.
Designed for use with the OEM turbocharger or factory-style drop-in upgrades, this down pipe improves exhaust flow, helps reduce EGT's, and sets the foundation for any high-flow exhaust system or turbo upgrade. No tuning is required, making it a simple, high-impact bolt-on for your LLY/LBZ/LMM Duramax.
Key Features & Benefits
- Full 3" turbo down pipe for 2004.5-2010 6.6L LLY/LBZ/LMM Duramax trucks.
- Replaces the restrictive crushed-style factory down pipe for improved exhaust flow.
- High-temp black ceramic coating for durability and reduced radiant heat.
- Heat wrap and clamps included to further control under-hood temperature.
- Compatible with OEM turbo and factory-style drop-in turbochargers.
- No tuning required — bolt-on upgrade when installed with a matching exhaust system.
- Excellent pairing with performance exhaust, intercooler piping, turbo kits, and coolant pipe upgrades.
- For off-road / competition use in many regions (check your local regulations).
What's Included
- Wehrli WCF100120 3" turbo down pipe (steel, mandrel-style).
- Heat wrap for down pipe.
- Heat wrap clamps / ties.
- Black high-temp ceramic coating on pipe.
- Installation hardware as supplied by Wehrli Custom Fab.
Vehicle Fitment
Engineered specifically for VGT turbo 6.6L Duramax LLY/LBZ/LMM platforms:
- 2004.5-2010 Chevrolet Silverado 2500HD / 3500HD 6.6L Duramax LLY/LBZ/LMM
- 2004.5-2010 GMC Sierra 2500HD / 3500HD 6.6L Duramax LLY/LBZ/LMM
This down pipe is designed to work with the factory-style VGT turbocharger and a compatible 3" front pipe / exhaust system. It is not intended for 2011+ LML trucks or earlier LB7 models — use the correct Wehrli down pipe for those applications.
Installation & Technical Notes
- Direct replacement for the OEM turbo down pipe / front pipe on 2004.5-2010 LLY/LBZ/LMM trucks.
- For use with factory turbo or factory-style drop-in VGT turbochargers.
- No ECM tuning required when installed with a properly sized exhaust system.
- Includes heat wrap and clamps; professional installation is recommended due to tight clearances.
- Replaces GM down pipe part number 98050150.
- Many trucks will require loosening or removing associated exhaust components for access; penetrating oil and patience go a long way on higher-mileage vehicles.
Emissions & Shipping Notice
- Intended for off-road/competition-only use where permitted by law.
- Not legal for sale or use on pollution-controlled vehicles in some areas.
- This product cannot be shipped to California where applicable emissions restrictions apply.
Recommended Wehrli & CPP Diesel Upgrades
Build a stronger, cleaner, and more reliable Duramax exhaust and under-hood package by pairing the WCF100120 down pipe with these Wehrli components available from CPP Diesel:
- WEHRLI WCF100703 04.5-10 DURAMAX LLY/LBZ/LMM 3IN STAINLESS DOWN PIPE – stainless version for corrosion resistance and show-quality builds.
- WEHRLI WCF100240 01-16 DURAMAX UP PIPE BOLT KIT – ARP fasteners for reliable up-pipe connections on LB7-LML platforms.
- WEHRLI WCF100189 04.5-2010 DURAMAX LLY/LBZ/LMM CRANKCASE VENT (PCV) FITTING KIT – billet PCV fittings to replace fragile factory plastic pieces.
- WEHRLI WCF100622 2006-2010 LBZ/LMM DURAMAX UPPER COOLANT PIPE – aluminum upper coolant pipe with silicone boots and T-bolt clamps.
Specifications
| Specification | Details |
|---|---|
| Brand | Wehrli Custom Fab (WCFab) |
| Manufacturer Part Number | WCF100120 |
| CPP Diesel SKU | WCF100120 |
| Engine Application | 6.6L Duramax LLY / LBZ / LMM |
| Model Years | 2004.5-2010 Chevrolet & GMC 2500HD / 3500HD |
| Pipe Diameter | 3" (76 mm) down pipe |
| Construction | Steel down pipe with high-temp black ceramic coating |
| Included Components | 3" down pipe, heat wrap, clamps, coated finish |
| Turbo Compatibility | OEM VGT turbo or factory-style drop-in turbocharger |
| Coating & Thermal Management | Black high-temp ceramic coated pipe with included heat wrap |
| Replaces GM Part Numbers | 98050150 (factory down pipe) |
| Shipping Weight (approx.) | ~5.5-6.0 lb |
| Package Dimensions (approx.) | 24.3" (L) x 7.0" (W) x 6.3" (H) |
| Use | Off-road / competition use only where permitted by law |
| California Shipping | Not for sale or shipment into California where restricted |
| Prop 65 Warning (California) | WARNING: Cancer and Reproductive Harm – www.P65Warnings.ca.gov |
FAQ
Does the WCF100120 3" down pipe require custom tuning?No. This down pipe is designed to work with the factory VGT turbocharger and properly matched exhaust system without requiring ECM tuning. As with any performance modification, it's still good practice to monitor EGT, boost, and overall engine health after installation.
Will this down pipe fit my 2011+ LML Duramax?
No. The WCF100120 is built specifically for 2004.5-2010 LLY/LBZ/LMM trucks. 2011+ LML trucks have different exhaust layouts and flange styles. Use the correct Wehrli LML down pipe, such as WCF100121 or other LML-specific part numbers, for 2011 and newer applications.
Can I use this with an aftermarket exhaust system?
Yes. The WCF100120 is commonly installed together with high-flow aftermarket exhaust systems. As long as the exhaust uses the appropriate connection style for the OEM down pipe location, this Wehrli unit will integrate just like the factory front pipe while providing better flow.
Why does the down pipe include both ceramic coating and heat wrap?
The ceramic coating helps keep exhaust energy in the flow path and protects the pipe from corrosion, while the added heat wrap further reduces under-hood radiant heat. This combination helps lower engine bay temperatures, protects nearby components, and maintains exhaust gas velocity for better spool and performance.
Is this product legal for on-road use and can it ship to California?
Many regions classify high-flow down pipes as competition or off-road-only parts when they alter or replace factory emissions-related components. Due to these regulations, this product is not for sale or shipment into California where such parts are restricted. Always check and comply with your local emissions and inspection laws before installation on a street-driven vehicle.
