FITMENT

• 2011-2015.5 6.6L Silverado & Sierra Duramax 2500HD/3500HD LML engine with a V-Band Clamp.
• Does NOT Fit 2015.5-2016 models equipped with the 3-bolt flange. Please check underneath your truck!
• Please physically inspect underneath your truck to verify your turbo discharge style before purchasing!

DESCRIPTION

Product Overview

• The early-generation 2011-2015 Duramax LML features a highly complex triple-emissions system (DPF + DOC + SCR/DEF) that chokes your engine.
• With 11 to 15.5 years on the road, these trucks have hit the peak failure window. Failed DEF heaters, drifting NOx sensors, and ash-plugged filters continuously throw fault codes, tank fuel mileage to a miserable 13-14 MPG, and trigger Limp Mode.
• Furthermore, pushing heavy loads through steep highway grades with these restrictions traps intense backpressure, which spikes towing EGTs past 1,300°F. At this vehicle age, simply patching the mid-section is not always enough; the factory rear tailpipe and hangers are often heavily rusted, scaled, and ready to snap.

Key Features

• Rugged T-409 Stainless Steel Build: Manufactured from industrial-grade T-409 SS, perfectly optimized to expand and contract under intense thermal cycling without cracking or warping.
• Substantial EGT & Heat Reduction: Instantly drops exhaust backpressure, allowing scorching gases to exit the motor rapidly, dropping EGTs significantly under heavy sustained towing loads.
• Continuous 4" Mandrel-Bent Tubing: Engineered with smooth, 4" diameter paths featuring zero internal neck-downs or restrictive bungs, providing the ultimate sweet spot for exhaust gas velocity.
• Complete Downpipe-Back Solution: Replaces the entire under-car system from the turbo downpipe rearward. Ideal for trucks where the original rear piping and hangers are rusted out after over a decade on the road.

FAQ

Q: Will this full 4" system fit my 2011-2015 Duramax LML truck?

A: Yes, if your truck features the factory V-band clamp style connection at the turbo downpipe output. This covers 11-15.5 production models. It does not fit Cab & Chassis trucks. If your truck is a 15.5-16 model equipped with a 3-bolt flange connection, you will need specific 15.5-16 late-model version.

Q: What is the difference between a mid-section delete pipe and this full DP-Back system?

A: A mid-section delete pipe only replaces the DPF and CAT filter blocks under the cab while forcing you to reuse your original factory tailpipe. This full system replaces everything from downpipe connection all the way to the rear exhaust exit tip. If your truck's original tailpipe or hangers are heavily rusted, this full kit is the proper choice.

Q: Do I still need a performance tuner with this full system?

A: Yes, absolutely. The truck’s computer (ECM) continuously monitors the pressure differences, DEF systems, and NOx sensors. Physically removing the DPF and CAT core will trigger fault codes and force the truck into instant Limp Mode within a few miles unless a delete-capable tuner (like Mini Maxx V2) is installed to turn off the emissions tracking software.

Q: What should I do with the exposed factory wiring connectors left under the truck?

A: Seal them to prevent corrosion and electrical shorts. Leaving unplugged factory connectors open to road salt, mud, and water can destroy sensitive electronics. We highly recommend using our LML Tuner Harness Plugs, which snap directly into your factory EGR/DPF connectors for a clean, weather-resistant seal.