Upgraded 3'' Downpipe Exhaust for 2015.5-2016 LML 6.6L Duramax Diesel 304 Stainless | SPELAB

Direct-fit 3-inch high-flow downpipe for 2015.5-2016 6.6L LML Duramax Diesel. Replaces the restrictive factory pipe to reduce exhaust backpressure, improve turbo response, lower EGTs, and boost overall truck performance for daily driving and heavy towing.

Key Features

• Premium 304 Stainless Steel Pipe: Mandrel-bent smooth pipe wall for maximum exhaust flow, rust and corrosion resistant for all-weather use.
• Durable Heat Insulation: Upgraded basalt heat wrap effectively reduces engine bay temperature and protects peripheral parts from heat damage.
• Sturdy Iron Flange: Equipped with thickened iron flange, high strength, pressure-resistant and leak-proof, ensures tight and stable installation, no exhaust leakage under high temperature.
• Direct Bolt-On Fit: Precisely engineered for 2015.5-2016 LML Duramax, reserves all factory sensor ports, no cutting or drilling required for easy installation.

Color Option

Silver (Raw 304 Stainless Steel)

• Brushed metallic finish with classic industrial texture
• Easy to clean and maintain, scratch restorable, maximum durability
• Ideal for users pursuing long-term use and simple maintenance

Black (High-Temperature Coated)

• Sleek matte black racing finish for aggressive modified look
• High-temperature resistant coating, no peeling or blistering
• Covers minor welding marks for a neater overall appearance
• Perfect for truck show and modification enthusiasts
  

Who This Is For

2015.5-2016 Chevrolet Silverado / GMC Sierra 2500/3500HD owners with the 6.6L LML Duramax who want a premium upgraded 3" downpipe with 304 stainless steel pipe + flange and heat wrap.

Product Specifications

• Engine: GM Duramax 6.6L LML Turbo-Diesel
• Pipe Diameter: 3 inch
• Material: 304 Stainless Steel (pipe + flange)
• Surface Options: Brushed Silver / High-Temp Black Coated
• Heat Wrap: Black fiberglass (upgraded from natural linen)
• Configuration: Catless
• Flange Type: Bolt-on (3-Bolt) + V-Band + O2 sensor bungs
• Weight: 4.89 kg (4890 g)

What's Included

• Downpipe
• Gasket(s)
• V-Band clamp(s)
• O2 sensor bungs
• Black fiberglass heat wrap
• Mounting hardware

Vehicle Fitment

Compatible vehicles: 2015.5–2016 Chevrolet Silverado 2500HD, Chevrolet Silverado 3500HD, GMC Sierra 2500HD, and GMC Sierra 3500HD. Will NOT fit Cab & Chassis trucks.

Check Before Choosing

• Cab & Chassis exclusion: Will NOT fit Cab & Chassis trucks — only fits pickup models.
• Tune required for delete: Yes — a diesel tune is required to clear the CEL/DPF codes and safely manage the increased flow.
• Version upgrade: New version is fully upgraded to 304 stainless steel pipe + 304 stainless steel flange (vs. old 201 SS + iron flange).
• Color options: Brushed Silver (classic) or High-Temp Black Coated (racing).
• Street legality: No — off-road / competition use only.

Installation Guide

Pre-Installation Checklist

• Confirm your engine code and model year match the fitment list above
• New gaskets and mounting hardware ready
• 22mm slotted O2 sensor socket + PB Blaster on hand
• a diesel tune to clear CEL/DPF codes

Installation Steps

1. Lift the vehicle and secure it on jack stands
2. Soak the O2 sensors and flange bolts with PB Blaster for 30+ minutes
3. Unplug and remove the O2 sensors with the slotted socket
4. Remove the factory downpipe and discard the old gasket
5. Bolt on the new downpipe with a fresh gasket
6. Reinstall and reconnect the O2 sensors
7. Flash your tune to suppress the check engine light

Installation Notes

• Never reuse the old gasket — it will cause an exhaust leak
• Use a slotted O2 socket, not a wrench — the sensor threads strip easily
• A catless downpipe triggers a CEL until the ECU is tuned
• Expect a stronger raw exhaust smell (normal for catless)

FAQ

Does it fit Cab & Chassis trucks?

No — this SKU is for pickup models only.

Does it fit 2011-2015 LML?

No — this SKU is for 2015.5-2016 LML. Earlier LML (2011-2015) uses a different SKU.

What is the difference vs. the old version?

The new version uses 304 stainless steel pipe + flange (vs. 201 SS + iron), and black fiberglass heat wrap (vs. natural linen).

Do I need a tune?

A diesel tune is required to clear the CEL/DPF codes and safely manage the increased flow.

Is it street-legal?

No — off-road / competition use only.