GM Duramax LMM Downpipe Back Exhaust (2007.5-2010)
Type: Exhaust Systems
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Open up your LMM’s airflow and let it breathe. Designed for 2007.5–2010 Silverado and Sierra 2500HD/3500HD pickups equipped with the 6.6L Duramax LMM, this downpipe-back exhaust system improves exhaust efficiency, lowers backpressure, and produces a deep, aggressive tone built for off-road performance applications.
For off-road and competition use only.
This LMM downpipe-back system replaces the restrictive factory exhaust from the downpipe rearward. Available in both 4-inch and 5-inch mandrel-bent configurations, it is engineered to support increased exhaust flow, improved throttle response, and reduced exhaust gas temperatures (EGTs) under load. Built from durable T409 stainless steel, it is designed to handle high-heat and high-vibration environments common in performance and towing applications.
Vehicle Fitment
- Years: 2007.5–2010
- Makes: Chevrolet Silverado / GMC Sierra
- Models: 2500HD, 3500HD (Pickup Only)
- Engine: 6.6L Duramax LMM Diesel
- Cab Styles: Extra Cab (EC), Crew Cab (CC)
- Box Lengths: Short Box (SB), Long Box (LB)
- Rear Configurations: Single Rear Wheel (SRW) & Dually (DRW)
Not Compatible With: Cab & Chassis models or 3-bolt flange configurations.
Available Sizes
- 4-Inch System: Balanced fitment with strong flow and refined tone
- 5-Inch System: Maximum airflow and deeper exhaust sound
Technical Specifications
| Material | 16-Gauge T409 Stainless Steel |
| Tubing Diameter | 4” or 5” Mandrel-Bent |
| Configuration | Downpipe-Back, Single Outlet |
| Clamps | Stainless Steel Band Clamps |
| Finish | Natural Brushed Stainless |
| Intended Use | Off-Road / Competition |
Features
- Mandrel-bent piping to maintain consistent diameter and smooth flow
- Heavy-duty 16-gauge stainless construction for strength and corrosion resistance
- Contour-bent hangers for stable, rattle-free alignment
- Pre-welded flanges for simplified installation
- High-quality stainless band clamps for secure, leak-resistant connections
- Clean, unrestricted design without sensor bungs
- Optional muffler configuration available for reduced sound levels
Performance Benefits
- Improved exhaust flow for stronger overall performance
- Reduced backpressure for quicker throttle response
- Lower EGTs during towing and heavy load conditions
- Durable materials built for high-heat diesel applications
- Deep, aggressive exhaust tone suited for performance builds
Installation & Important Notes
- Direct bolt-on design—no cutting or welding required.
- Reuses factory-style hanger locations for proper alignment.
- Professional installation recommended for best fitment and clearance.
- Proper race tuning is required for optimal performance.
- For competition/off-road use only. Verify local regulations before installation.
Important Notes:
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Important Notices
- Off‑Road Use Only
Products sold by JS Speed are intended for off‑road use and may be illegal on public roads where emissions or pollution‑control laws apply. - Check Local Laws
Before purchasing or installing, verify all applicable local, state/provincial, and federal regulations to ensure the modification is legal in your area. - Professional Installation Recommended
These parts should be installed by qualified professional mechanics. Improper installation can cause performance issues or vehicle damage. Unless a product page explicitly states otherwise, installation instructions are not included. Components are designed for users with solid mechanical knowledge, and minor adjustments or modifications may be required for proper fitment. Returns or refunds cannot be accepted due to difficulty completing an installation or the absence of instructions. - Warranty Impact
Use of these parts may void your vehicle’s factory warranty. Confirm with your vehicle manufacturer before purchase and installation. - Limitation of Liability
JS Speed is not responsible for damage, failures, or issues arising from the use or installation of these products. - Product Images
Images are for illustration only and may differ from the actual product due to manufacturer updates or improvements. - No Performance Guarantees
While these products are designed to enhance performance, JS Speed does not guarantee specific performance results.
