4″ Exhaust | DURAMAX EXHAUST KITS | LML 2011–2015

Upgrade your LML Duramax with this 4″ exhaust system designed for maximum flow, lower EGTs, and long-term durability. By replacing restrictive factory components, this system improves turbo response, efficiency, and sound. Available in multiple configurations, you can choose between straight pipe or muffler, and add an up-pipe or down-pipe for even more performance. Built from heavy-duty materials, this exhaust kit delivers the power and reliability your truck deserves.

What’s Included

• 4″ Downpipe-Back Exhaust System – Full system replacement from turbo downpipe to tailpipe

• Mandrel-Bent Tubing – Smooth 4″ design ensures unrestricted flow and durability

• High-Quality Clamps & Hardware – Leak-free, secure installation

• Available Options:

  • Straight Pipe – Maximum flow and aggressive exhaust tone

  • With Muffler – Quieter, refined sound with reduced in-cab drone

  • Add Up-Pipe – Improves flow from turbo to exhaust for additional reliability and performance

  • Add Down-Pipe – Freer turbo outlet for quicker spool and better efficiency

Vehicle Fitment

• Chevrolet Silverado 2500HD / 3500HD – 6.6L Duramax LML

• GMC Sierra 2500HD / 3500HD – 6.6L Duramax LML

• Model Years: 2011, 2012, 2013, 2014, early-2015

• Not designed for Cab & Chassis models

The year 2015 is a split year, with the 2011-2015 downpipe secured to the turbo-direct pipe using a V-band style clamp. The 2015.5-2016 model, on the other hand, uses a 3-bolt flange style connection. Be sure to visually verify the style of clamp your truck is equipped with.

Important Reminder: To ensure smooth operation and prevent check engine lights (CELs) or dash warnings, this exhaust system requires compatible tuning. For optimal performance and seamless integration, we recommend pairing it with the EFI Live AutoCal V3 tuner.

Benefits & Features

• Lower EGTs – Keep exhaust gas temperatures down during towing and heavy-duty work

• Improved Turbo Response – Reduced backpressure helps your turbo spool faster and more efficiently

• Better Fuel Efficiency – Freer flow contributes to improved mileage potential

• Sound Options – Choose straight pipe for raw tone or muffler for a moderate sound profile

• Up-Pipe/Down-Pipe Options – Optimize airflow at critical points in the exhaust system

• Durable Construction – Built to withstand heat, corrosion, and long-term heavy use

• Direct-Fit Design – Engineered specifically for LML Duramax trucks for smooth installation

Emissions & Legal Use Disclaimer

For off-road use only. Not legal for use on public roads. Always check local and federal emissions regulations before purchasing or installing this product.

Build the Perfect Exhaust Setup for Your Duramax

Order your 4″ exhaust system today and configure it your way — straight pipe or muffler, with or without up-pipe and down-pipe — to get the exact performance and sound your LML deserves.