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 11-15.5 6.6L Duramax LML is an incredible workhorse, but it is notorious for being heavily strangled by its complex first-generation DEF/SCR and DPF/CAT emissions systems. As these trucks age, the factory DPF ceramic core plugs up permanently with non-burnable ash.
• This results in your truck entering endless Active Regeneration cycles, which forcefully dumps raw diesel into the exhaust stroke just to heat up the filter.
• Your fuel economy tanks to a miserable 13-14 MPG, your EGTs skyrocket, and the immense backpressure puts extreme fatigue on turbocharger, frequently dropping the truck into Limp Mode.

Key Features

• True 4" Mandrel-Bent Flow: CNC mandrel-bent 4" T-409 SS tubing ensures smooth, high-velocity exhaust flow. Completely unrestricted with No Bungs to interrupt the air path.
• Massive Fuel Mileage Gains: Eliminates the fuel-hungry active regeneration process. Most LML owners see fuel economy recover from a clogged 13 MPG up to a clean 18-19 combined MPG on the highway.
• Drastic EGT & Backpressure Relief: Allows hot exhaust gases to escape instantly right out of the downpipe. This reduces structural heat-soak and lowers EGTs, protecting your turbocharger under heavy towing loads.
• Integrated Performance Muffler: Specifically engineered to deliver full backpressure relief while trapping harsh high-frequency exhaust notes and eliminating painful cabin drone during long highway towing hauls.

FAQ

Q: What is the difference between this 11-15.5 and 15.5-16?

A: The turbo downpipe outlet flange changed midway through 2015. This pipe fits the early 11–15.5 V-band style clamp, while our 15.5–16 pipe fits the late-generation 3-bolt flange. Under-truck exhaust routing and hanger locations are otherwise identical.

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

A: Yes, absolutely. Removing the catalytic converter and DPF changes the pressure readings monitored by the ECM. You MUST run a delete-capable programmer (like Mini Maxx tuner) to turn off emissions tracking, stop DPF regeneration cycles, and prevent the truck from entering Limp Mode.

Q: How much will this kit improve my LML's fuel economy (MPG)?

A: Most owners see a massive jump. While a clogged factory DPF drops fuel economy to 13–14 MPG due to frequent regenerations, this pipe and a proper tune can restore combined mileage to 18–19 MPG under normal driving conditions.

Q: Why do I need an EGR Delete and CCV Reroute along with this exhaust setup?

A: To stop tar-like sludge from choking your intake. This pipe fixes your exhaust, but your intake still faces oily CCV mist and abrasive EGR soot that block airflow and spike EGTs. Pairing this upgrade with an LML EGR Delete and CCV Reroute stops sludge build-up and prevents coolant leaks, ensuring 100% clean airflow.