4"/5" 2011-2015 LML 6.6 Duramax Down-pipe Back Exhaust

*Race and off-road use only*

4” / 5” Downpipe-Back Exhaust System

2011–2015 Duramax 6.6L LML

*Race and off-road use only*

Upgrade the exhaust flow and sound of your 2011–2015 Duramax LML with this 4” or 5” downpipe-back exhaust system, manufactured by SPELAB and independently retailed by Secret Diesel Performance.

This system is designed to replace the restrictive factory exhaust from the downpipe back, allowing for improved exhaust flow, reduced backpressure, and a deeper, more aggressive exhaust note. Whether your truck is built for towing, off-road use, or performance applications, this exhaust provides a strong foundation for improved power delivery and future modifications.

Built with durability and proper fitment in mind, the modular design allows for straightforward installation and reliable long-term performance.

Features & Benefits

• Downpipe-back exhaust system for Duramax 6.6L LML engines
• Available in 4” or 5” diameter configurations
• Improved exhaust flow and throttle response
• Deeper, more aggressive exhaust tone versus stock
• Direct replacement for factory exhaust components
• Engineered for race and off-road performance applications

Fitment

• 2011–2015 Chevrolet Silverado 2500HD / 3500HD
• 2011–2015 GMC Sierra 2500HD / 3500HD
• 6.6L Duramax LML

Important Notes

• Intended for race and off-road use only
• Not legal for use on public roads in some states
• Professional installation recommended
• Product is independently retailed and not affiliated with or endorsed by the vehicle manufacturer