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2015.5-2016 LML Duramax 3-Inch Downpipe Overview

Reduce turbo-outlet restriction with a direct-fit 3-inch LML Duramax downpipe built specifically for 2015.5-2016 Chevrolet Silverado and GMC Sierra 2500HD/3500HD pickups. Its straight-through catless design supports smoother exhaust flow, quicker turbo response and lower EGTs under load, while the upgraded 304 stainless steel pipe and flange provide better corrosion and heat resistance than the previous 201 stainless steel and iron-flange version.

Check before ordering: This downpipe is for pickup models equipped with the later 2015.5-2016 three-stud turbo-side connection. It does not fit early 2015 trucks with the earlier connection or Cab & Chassis applications. Choose Silver for a raw stainless finish or Black for a high-temperature-coated appearance.

Specification

Key Features

• Straight-through 3-inch flow path: Reduces exhaust restriction at the turbo outlet to support quicker turbo response, lower EGTs under load and improved exhaust flow.
• Mandrel-bent tubing: Maintains a smooth internal flow path through the bends to help reduce unnecessary restriction and support consistent exhaust flow.
• Full 304 stainless construction: Both the pipe and flange use 304 stainless steel for improved corrosion resistance and thermal stability.
• Black fiberglass heat wrap: Helps limit radiant heat around nearby wiring, hoses and other heat-sensitive engine-bay components.
• Application-specific connections: Designed around the later LML three-stud turbo flange, V-band outlet and factory-style sensor locations.
• Direct-fit installation: Cutting or drilling is not normally required on an unmodified pickup with the correct connection style.
• Two finish choices: Silver leaves the stainless surface exposed for easy inspection, while Black provides a darker high-temperature-coated appearance.

Package Include

• Downpipe in the selected Silver or Black finish
• Gasket(s)
• V-band clamp(s)
• Integrated O2 sensor bungs
• Black fiberglass heat wrap
• Mounting hardware

This package contains the turbo-outlet downpipe only. It is not a complete DPF/SCR exhaust system, EGR delete kit or tuner.

Upgrade Version vs. Old Version: What Changed?

The new 3-inch model is a dedicated 2015.5-2016 LML upgrade. The previous 3.5 inch LML downpipe old version remains an alternative for buyers comparing the earlier multi-generation design.

Choose the new version when your priority is confirmed 2015.5-2016 fitment, full 304 stainless construction and the upgraded black heat wrap. Choose by verified vehicle connection and intended setup—not pipe diameter alone.

Important Notes

• Off-Road Use Only: This catless downpipe is intended for off-road or competition applications and is not represented as CARB- or EPA-certified for emissions-compliant highway use.
• Check Local Laws: Removing, bypassing or disabling required emissions equipment may violate federal, state or local law. Review the product-use notice before purchase or installation.
• Tuning Required: A catless configuration may trigger a check-engine light or related diagnostic codes. The official product information states that appropriate diesel calibration is required. Calibration must be completed only where lawful and by a qualified professional.
• Exhaust Odor: A catless configuration may produce a stronger raw exhaust odor than the factory emissions-equipped system.
• Professional Installation Recommended: Verify the flange, sensor arrangement, gasket, hardware and surrounding clearance before final assembly.
• Vehicle Warranty: Aftermarket exhaust modifications may affect vehicle-manufacturer warranty coverage. Confirm the applicable terms before installation.
• Performance Results: Turbo response, EGT, sound and power changes depend on the truck’s condition, calibration and complete exhaust configuration. No fixed horsepower gain is promised.

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2015.5-2016 LML Duramax Downpipe Fitment

Fits the following Chevrolet and GMC pickups with the 6.6L LML Duramax and later three-stud turbo-side connection. Does not fit Cab & Chassis trucks.

Confirm the Split-Year Connection Before Ordering

• Later 2015.5-2016 trucks: Use the three-stud triangular turbo-side connection required by this downpipe.
• 2011-early 2015 trucks: Use a different turbo-side connection and require the earlier-fitment downpipe.
• Turbo-side opening: Approximately 67 mm.
• Downstream V-band outlet: Approximately 72.5 mm.
• Sensor layout: One M14 and two M20 threaded ports. Compare the locations with the original pipe before disassembly.

Do not order by registration year alone when working with a 2015 truck. Inspect the original turbo-side connection before purchase.

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Installation

1. Confirm the 2015.5-2016 LML engine, pickup chassis and three-stud turbo connection before removing the original pipe.
2. Allow the engine, turbo and exhaust to cool completely, then secure the truck on a rated lift or jack stands.
3. Apply penetrating oil to the sensor threads and flange hardware for at least 30 minutes. Use a 22 mm slotted sensor socket where applicable.
4. Disconnect and remove the sensors without twisting their wiring, then remove the factory downpipe and old gasket.
5. Compare the new flange, outlet and sensor-port locations with the original pipe before installation.
6. Install the new downpipe with the supplied or vehicle-required fresh gasket and hardware. Reinstall the required sensors and align the pipe before final tightening.
7. Complete any required calibration for lawful off-road or competition use through a qualified diesel professional before operating the truck. A catless configuration may trigger a check-engine light or related diagnostic codes without the appropriate calibration.
8. Inspect every connection for leaks, contact or wiring-clearance problems, then recheck the system after a complete heat cycle.

Professional installation is recommended. Corrosion, previous exhaust work or non-stock adjoining components can change the tools, hardware or adjustments required.

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2015.5-2016 LML Downpipe FAQ

Q: Will this downpipe fit my 2015 Duramax?

A: Only if it is the later 2015.5 pickup configuration with the 6.6L LML engine and matching three-stud turbo-side connection. Early 2015 trucks use a different downpipe connection.

Q: Does it fit Cab & Chassis trucks?

A: No. This SKU is listed only for Silverado and Sierra 2500HD/3500HD pickup applications.

Q: What changed compared with the old version?

A: The new version changes from a 3.5 inch multi-generation design to a dedicated 3-inch 2015.5-2016 application. It also upgrades the previous 201 stainless steel pipe and iron flange to 304 stainless steel for both components and replaces the natural-color wrap with black fiberglass heat wrap.

Q: What comes with the downpipe?

A: The official package list includes the selected downpipe, gasket(s), V-band clamp(s), integrated sensor bungs, black fiberglass heat wrap and mounting hardware. A tuner, EGR kit and downstream exhaust system are not included.

Q: Does installation require cutting or welding?

A: Cutting or welding is not normally required on an unmodified pickup with the correct three-stud and V-band connections. Previous exhaust modifications, corrosion or mismatched adjoining parts can change the installation requirements.

Q: Does this catless LML downpipe require tuning?

A: Yes. A catless configuration may trigger a check-engine light or related diagnostic codes without the appropriate diesel calibration. Any required calibration must be performed only for lawful off-road or competition use by a qualified diesel professional.

Q: Will a catless downpipe change the exhaust odor?

A: It may. Removing the factory restriction can produce a stronger raw exhaust odor than the original emissions-equipped system.

Q: Is this LML downpipe legal for street use?

A: It is sold for off-road or competition use and is not represented as CARB- or EPA-certified for emissions-compliant street operation. Confirm all federal, state and local requirements before purchase or installation.

Shipping, Returns, Warranty and Compliance

Shipping

Orders are generally processed within 1-2 business days. The current policy lists standard U.S. delivery at 7-15 working days and express U.S. delivery at 2-7 working days. Delivery estimates are not guarantees. View the current Shipping Policy

Returns

Return or exchange requests must be made within 30 days of receipt. Products must be unopened, unused and in the original packaging with tags attached. Non-defective return shipping is generally the buyer's responsibility. Confirm fitment before installation because used products do not qualify under the stated return conditions. View the current Refund Policy

Warranty

This listing is presented with a 1-year warranty. Eligibility, coverage, exclusions and claim requirements are subject to the terms in effect when the claim is made. Contact SPEtuner Support

Use and Compliance

Confirm that the vehicle configuration and intended use comply with all applicable laws before purchase or installation. Competition or off-road labeling does not by itself establish legality, and installation may affect the vehicle manufacturer's warranty. Review the current product notice