FITMENT
- 2007.5-2010 6.6L Silverado & Sierra Duramax 2500HD/3500HD LMM engine.
- Fits Crew Cab Short Bed and Crew Cab Long Bed models. Does NOT Fit: Cab & Chassis truck models.
DESCRIPTION
Product Overview
- The 2007.5–2010 Chevrolet Silverado and GMC Sierra 2500HD/3500HD 6.6L Duramax LMM marked General Motors' introduction of factory DPF emissions technology. However, this early DPF system is notorious for high backpressure, frequent fuel-wasting active regens, and dangerous thermal heat build-up right behind the turbo.
- The 5" Downpipe-Back DPF & DOC Delete Race Exhaust Kit is engineered specifically to liberate the LMM engine. By removing the choked emissions core at the source, it sharply drops towing EGTs, restores crisp throttle response, improves fuel economy by 2–3 MPG, and delivers that deep, unmistakable Duramax V8 rumble.
Key Features
-
Premium T409 Stainless Steel: Full 5-inch mandrel-bent T409 stainless steel tubing built to withstand extreme exhaust temperatures, road salt, and harsh off-road environments.
- Sharply Lower Towing EGTs: Eliminates intense exhaust backpressure right behind the downpipe, allowing exhaust gases to flush out rapidly to lower Exhaust Gas Temperatures (EGTs) under heavy towing.
- Permanently Kill Active Regens: Stops fuel-wasting active regeneration cycles that inject raw diesel during exhaust strokes, protecting crankcase oil from fuel dilution and bearing wear.
- Direct Bolt-On Fitment: Connects directly to the factory downpipe outlet flange and mounts using stock rubber hangers—no custom welding required.
FAQ
Q: What is the sound and performance difference between a 4" and a 5" kit for the LMM Duramax?
A: 4"pipe produces a sharper, higher-pitched turbo whistle. A 5" pipe acts like a natural megaphone, deepening the exhaust note into a much lower V8 bass at idle and a thunderous roar under load. Performance-wise, a 5" pipe supports higher airflow for heavily tuned trucks or upgraded turbo setups.
Q: Will a 5" Downpipe-Back exhaust fit trucks equipped with rear air helper springs (Air Bags)?
A: Yes. The rear axle over-bend tubing is CNC mandrel-bent to follow OEM routing contours, providing safe operating distance around popular aftermarket tow-helper air bag kits (such as Air Lift or Firestone Ride-Rite), heavy-duty shocks, and rear sway bars.
Q: Why doesn't this 5" LMM kit replace the front downpipe off the turbo?
A: This is a Downpipe-Back system, meaning it connects to the outlet flange of your factory front downpipe. The stock LMM downpipe is flattened for body clearance, but replacing the entire DPF and DOC behind it eliminates 85%+ of total exhaust restriction. If you want even more airflow, you can pair this kit with an aftermarket high-flow 3" downpipe.
Q: Will this 5" system fit both Single Rear Wheel (SRW) and Dual Rear Wheel (Dually) trucks?
A: Yes. It is fully compatible with both SRW and DRW (Dually) 2500HD and 3500HD models across all cab and bed lengths.
