3.5'' Downpipe Exhaust For 2017-2024 L5P 6.6L Duramax Diesel Black| SPELAB
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---tab Description---
This 3.5" turbocharger downpipe will increase exhaust flow, improving performance.
Made with mandrel-bent 3.5-inch stainless steel tubing and coated in a ceramic black finish, this SPELAB high-performance L5P downpipe significantly improves airflow, reduces EGTs, and enhances turbocharger response. It’s the ideal component to begin building a full L5P Duramax downpipe delete system.
Whether you're replacing a restrictive stock pipe or upgrading for tuning purposes, this Duramax downpipe delivers the gains you expect in both performance and durability.
Black or Silver?
At SPELAB, our Standard Silver Stainless Steel Downpipe has long been the "Best Seller" and the go-to choice for truck owners, thanks to its exceptional value and time-tested reliability. If you are looking for a solid performance boost with a clean, factory-style finish, the Silver variant remains your most dependable partner on the road.
For enthusiasts seeking ultimate heat management and a premium custom look, our Black Ceramic Coated takes performance to the next level:
• Superior Thermal Control: The advanced ceramic coating effectively traps heat within the pipe, reducing under-hood temperatures and ensuring quicker turbo spool-up.
• All-Weather Protection: Especially in harsh environments or salted road conditions, the ceramic layer acts as an extra shield, providing superior resistance to corrosion and rust.
• Sleek Aesthetics: The deep matte black finish adds a professional, high-performance visual impact to your engine bay.
Specifications
Application:
Downpipe Exhaust
Material: Stainless Steel
Surface: Mirror Polish
Key Features
Complete Kit : Includes downpipe , heat wrap, clamps, and precision flanges
Superior Heat Control : Minimizes heat soak and improves turbo efficiency
Direct Fit : Designed to replace the 2018 L5P downpipe without cutting or welding
Ceramic Coating : Sleek finish with high resistance to corrosion and heat
OE vs. SPELAB Downpipe Comparison
Feature
Stock Downpipe
SPELAB 3.5" Downpipe
Pipe Diameter
Narrow, restrictive
Large 3.5-inch high-flow mandrel bent
Surface Protection
Bare metal, prone to rust
Black ceramic coating, high-temp and anti-corrosive
Weld Quality
Spot-welded, uneven
Precision full TIG-welded flanges
Heat Management
None
Includes thermal wrap + stainless clamps
Flow Efficiency
High backpressure, turbo lag
Smooth, unrestricted flow—ideal for L5P downpipe delete builds
What's the Difference Between a Downpipe and an Exhaust?
Component
Function Description
Location
Downpipe
Connects turbo outlet to mid-pipe; manages hot gas flow
Immediately after the turbocharger
Exhaust System
Mid-section to tailpipe; reduces noise and handles emissions
From downpipe to tailpipe
Upgrading the downpipe = performance and throttle response Upgrading the exhaust = tone, flow, and backpressure control
---tab Fitment---
• 2017-2024 Chevrolet Silverado & GMC Sierra 2500 & 3500HD 6.6L Duramax pickup trucks.
• Will not fit Cab & Chassis trucks.
---tab FAQ---
What does a downpipe do?
The downpipe on your turbocharged vehicle is directing the exhaust gases out of the turbine housing into the exhaust system. An aftermarket downpipe will typically be larger in diameter and either uses a high-flowing catalytic converter or remove the catalytic converter altogether.
By removing the factory downpipe and replacing it with a high flowing unit you are allowing the turbo to more efficiently move gases away from the turbine which creates more power. Since the factory restrictions are now gone you can increase the boost on the vehicle as the factory downpipe is a choking point for performance.
Q1: Is this SPELAB downpipe catless or catted? A: This is a catless downpipe , meaning it does not contain a catalytic converter. It’s designed for maximum exhaust flow and performance—ideal for off-road and race-use L5P Duramax downpipe delete builds.
Q2: What is the difference between a catted and a catless downpipe? A: A catted downpipe includes a high-flow catalytic converter and is more emissions-friendly, while a catless downpipe removes restrictions completely for maximum performance. SPELAB’s 3.5-inch downpipe is catless.
Q3: Do I need a tuner after installing this downpipe? A: If you’re using it as part of an L5P downpipe delete or DPF removal system, a tuner is required to prevent check engine lights and optimize performance.
Q4: Which model years does this downpipe fit? A: It fits all 2017–2024 L5P 6.6L Duramax trucks, including those needing a 2018 L5P downpipe replacement.
Q5: Can this downpipe work with the stock exhaust? A: Yes, it is compatible with both OEM mid/tail sections and aftermarket 4” or 5” Duramax exhaust systems.
Q6: Does installation require cutting or welding? A: No cutting or welding is needed. This is a bolt-on L5P Duramax downpipe that uses factory-style mounting points and flange connections.
Q7: Will this downpipe change my exhaust sound? A: Slightly. It deepens the tone and improves airflow. Paired with a full exhaust upgrade, the sound becomes much more aggressive.
Q8: What’s the wall thickness and corrosion resistance like? A: Made from thick 2mm stainless steel with ceramic coating, it provides excellent heat and corrosion resistance in all weather conditions.
Q9: Can I use this as part of a DPF delete system? A: Yes. It’s commonly used in L5P Duramax downpipe delete setups as the first step in removing stock emissions restrictions. Off-road use only.
Q10: Who should buy this 3.5-inch downpipe from SPELAB? A: It’s perfect for diesel enthusiasts looking to increase power, reduce turbo lag, and build a performance-tuned L5P truck for off-road or race use.
---tab Shipping & Returns---
Fast Shipping Policy
Your order will be dispatched within 1-2 business days , and the package will arrive within your order's estimated date. Click for Shipping Policy
Easy Return Policy
Every order comes with a 14-day free return , which means you don't have to pay for a return slip. Click for Return Policy
---tab Description---
This 3.5" turbocharger downpipe will increase exhaust flow, improving performance.
Made with mandrel-bent 3.5-inch stainless steel tubing and coated in a ceramic black finish, this SPELAB high-performance L5P downpipe significantly improves airflow, reduces EGTs, and enhances turbocharger response. It’s the ideal component to begin building a full L5P Duramax downpipe delete system.
Whether you're replacing a restrictive stock pipe or upgrading for tuning purposes, this Duramax downpipe delivers the gains you expect in both performance and durability.
Black or Silver?
At SPELAB, our Standard Silver Stainless Steel Downpipe has long been the "Best Seller" and the go-to choice for truck owners, thanks to its exceptional value and time-tested reliability. If you are looking for a solid performance boost with a clean, factory-style finish, the Silver variant remains your most dependable partner on the road.
For enthusiasts seeking ultimate heat management and a premium custom look, our Black Ceramic Coated takes performance to the next level:
• Superior Thermal Control: The advanced ceramic coating effectively traps heat within the pipe, reducing under-hood temperatures and ensuring quicker turbo spool-up.
• All-Weather Protection: Especially in harsh environments or salted road conditions, the ceramic layer acts as an extra shield, providing superior resistance to corrosion and rust.
• Sleek Aesthetics: The deep matte black finish adds a professional, high-performance visual impact to your engine bay.
Specifications
Application:
Downpipe Exhaust
Material: Stainless Steel
Surface: Mirror Polish
Key Features
Complete Kit : Includes downpipe , heat wrap, clamps, and precision flanges
Superior Heat Control : Minimizes heat soak and improves turbo efficiency
Direct Fit : Designed to replace the 2018 L5P downpipe without cutting or welding
Ceramic Coating : Sleek finish with high resistance to corrosion and heat
OE vs. SPELAB Downpipe Comparison
Feature
Stock Downpipe
SPELAB 3.5" Downpipe
Pipe Diameter
Narrow, restrictive
Large 3.5-inch high-flow mandrel bent
Surface Protection
Bare metal, prone to rust
Black ceramic coating, high-temp and anti-corrosive
Weld Quality
Spot-welded, uneven
Precision full TIG-welded flanges
Heat Management
None
Includes thermal wrap + stainless clamps
Flow Efficiency
High backpressure, turbo lag
Smooth, unrestricted flow—ideal for L5P downpipe delete builds
What's the Difference Between a Downpipe and an Exhaust?
Component
Function Description
Location
Downpipe
Connects turbo outlet to mid-pipe; manages hot gas flow
Immediately after the turbocharger
Exhaust System
Mid-section to tailpipe; reduces noise and handles emissions
From downpipe to tailpipe
Upgrading the downpipe = performance and throttle response Upgrading the exhaust = tone, flow, and backpressure control
---tab Fitment---
• 2017-2024 Chevrolet Silverado & GMC Sierra 2500 & 3500HD 6.6L Duramax pickup trucks.
• Will not fit Cab & Chassis trucks.
---tab FAQ---
What does a downpipe do?
The downpipe on your turbocharged vehicle is directing the exhaust gases out of the turbine housing into the exhaust system. An aftermarket downpipe will typically be larger in diameter and either uses a high-flowing catalytic converter or remove the catalytic converter altogether.
By removing the factory downpipe and replacing it with a high flowing unit you are allowing the turbo to more efficiently move gases away from the turbine which creates more power. Since the factory restrictions are now gone you can increase the boost on the vehicle as the factory downpipe is a choking point for performance.
Q1: Is this SPELAB downpipe catless or catted? A: This is a catless downpipe , meaning it does not contain a catalytic converter. It’s designed for maximum exhaust flow and performance—ideal for off-road and race-use L5P Duramax downpipe delete builds.
Q2: What is the difference between a catted and a catless downpipe? A: A catted downpipe includes a high-flow catalytic converter and is more emissions-friendly, while a catless downpipe removes restrictions completely for maximum performance. SPELAB’s 3.5-inch downpipe is catless.
Q3: Do I need a tuner after installing this downpipe? A: If you’re using it as part of an L5P downpipe delete or DPF removal system, a tuner is required to prevent check engine lights and optimize performance.
Q4: Which model years does this downpipe fit? A: It fits all 2017–2024 L5P 6.6L Duramax trucks, including those needing a 2018 L5P downpipe replacement.
Q5: Can this downpipe work with the stock exhaust? A: Yes, it is compatible with both OEM mid/tail sections and aftermarket 4” or 5” Duramax exhaust systems.
Q6: Does installation require cutting or welding? A: No cutting or welding is needed. This is a bolt-on L5P Duramax downpipe that uses factory-style mounting points and flange connections.
Q7: Will this downpipe change my exhaust sound? A: Slightly. It deepens the tone and improves airflow. Paired with a full exhaust upgrade, the sound becomes much more aggressive.
Q8: What’s the wall thickness and corrosion resistance like? A: Made from thick 2mm stainless steel with ceramic coating, it provides excellent heat and corrosion resistance in all weather conditions.
Q9: Can I use this as part of a DPF delete system? A: Yes. It’s commonly used in L5P Duramax downpipe delete setups as the first step in removing stock emissions restrictions. Off-road use only.
Q10: Who should buy this 3.5-inch downpipe from SPELAB? A: It’s perfect for diesel enthusiasts looking to increase power, reduce turbo lag, and build a performance-tuned L5P truck for off-road or race use.
---tab Shipping & Returns---
Fast Shipping Policy
Your order will be dispatched within 1-2 business days , and the package will arrive within your order's estimated date. Click for Shipping Policy
Easy Return Policy
Every order comes with a 14-day free return , which means you don't have to pay for a return slip. Click for Return Policy
SPELAB Auto Parts: 1 year from delivery; supplier conditions apply. SPELAB offers a one-year limited warranty from delivery for material/workmanship defects under normal use, original purchaser only, with proof of purchase. Consumables, wear/cosmetic damage, improper installation, alteration, misuse and removal/installation labor are excluded. Approved remedies are repair, replacement or replacement parts at SPELAB’s discretion.
Return and warranty information is based on what SPELAB Auto Parts offers. Product-specific eligibility and the supplier’s published conditions apply; FullSpecDiesel does not add or extend coverage.
SPELAB Auto Parts warranty policyView complete warrantyProduct conditions
Return and warranty information is based on what SPELAB Auto Parts offers. Product-specific eligibility and the supplier’s published conditions apply; FullSpecDiesel does not add or extend coverage.
- Return eligibility
- SPELAB allows return requests within 30 days of delivery, with authorization and undamaged goods, original packaging and accessories. Tuners are final sale. Customer pays voluntary return shipping; original shipping is not refunded. SPELAB pays return shipping for approved damaged, incorrect or manufacturing-defective items. Transit damage must be reported within two business days and incorrect items within seven days. Based on what SPELAB Auto Parts offers.
- Return window
- Not stated for this product; see supplier terms
- Restocking fee
- See supplier terms; no product-specific fee stated
- Return shipping
- Based on the supplier’s return policy; see terms
- Made to order
- No
- Backorder status
- Not backordered
- Cancellation
- Subject to supplier terms; contact FullSpecDiesel before requesting cancellation
- Warranty provider
- SPELAB Auto Parts
- Warranty duration
- 1 year from delivery; supplier conditions apply
- Compatibility
- Listed for specific vehicle configurations
- Legal use
- Street legal
- Processing estimate
- 3–10 business days supplier processing
- Shipping
- Shipping calculated at checkout
- Signature
- No signature requirement
- Supplier
- SPELAB Auto Parts
Product compatibility is based on the vehicle and product information provided. Review your selected truck, product options, measurements, modifications, and installation requirements before ordering.