4'” and 5'” Downpipe-Back exhaust 2001-2007 LBZ LLY LB7

*Race and off-road use only*

Take your 2001–2007 Duramax-powered truck to the next level with this 4” or 5” downpipe-back exhaust system, manufactured by SPELAB and independently retailed by Secret Diesel Performance.

Designed for diesel enthusiasts looking to improve exhaust flow and sound, this system replaces the restrictive factory exhaust from the downpipe back, allowing for reduced backpressure, improved throttle response, and a deeper, more aggressive exhaust tone. Ideal for performance builds, towing applications, and off-road use, this exhaust provides a solid foundation for future power upgrades.

Constructed from durable materials and engineered for proper fitment, the modular design allows for straightforward installation using basic hand tools.

Features & Benefits

• Downpipe-back exhaust system for Duramax LB7, LLY, and LBZ engines
• Available in 4” or 5” diameter configurations
• Improves exhaust flow and overall engine efficiency
• Aggressive exhaust tone compared to stock
• Direct replacement for factory exhaust components
• Engineered for race and off-road performance applications

Fitment

• 2001–2007 Chevrolet Silverado 2500HD / 3500HD
• 2001–2007 GMC Sierra 2500HD / 3500HD
• Duramax LB7, LLY, and LBZ engines

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