FITMENT
- 2017-2023 6.6L Silverado & Sierra Duramax 2500HD/3500HD trucks.
- Fit Crew Cab, Double Cab, Regular Cab with Standard/Long Bed.
- Does NOT Fit: 3500/4500/5500 Cab & Chassis commercial models.
DESCRIPTION
Product Overview
- The 2017–2023 Duramax L5P is heavily choked by two factory bottlenecks: the restrictive under-cab DPF/CAT filter blocks and the rough, narrow 3.5" downpipe directly behind the turbo. Over time, these components plug with ash, triggering frequent, fuel-guzzling regeneration cycles that drop mileage to a poor 12–14 MPG.
- Additionally, the fragile L5P emissions network is highly prone to DEF heater, pump, and NOx sensor failures that instantly trigger a 55 MPH Limp Mode countdown. Forcing exhaust through these combined restrictions traps intense backpressure, spiking towing EGTs past 1,300°F and shortening turbo life.
Key Features
- Industrial-Grade T-409 Stainless Steel: Crafted from heavy-duty mandrel-bent T-409 SS to withstand intense thermal expansion and contraction cycles without cracking, warping, or scaling.
- Ultimate EGT Heat Dissipation: Instantly dumps scorching exhaust gases from under the cab, significantly lowering engine and transmission operating temperatures under heavy sustained towing loads.
- Massive 5-Inch Competition Flow: Upgrades the entire path to a 5" diameter, dropping backpressure to near zero for maximum high-RPM power headroom and a thunderous, deep-bass V8 straight-pipe roar.
- Thick Machined L5P 4-Bolt Flange: Features a heavy-duty, flat-machined 4-bolt square flange that seals perfectly against your factory turbo direct downpipe output, ensuring zero leaks under intense boost.
FAQ
Q: What is the difference between the 4" DP-Back and this 5" DP-Back system?
A: The primary differences are diameter, sound volume, and power headroom. The 4" pipe flows more than enough for stock or street-tuned trucks. This 5" system adds maximum airflow capacity for heavily modified trucks (aftermarket turbos, larger injectors) and delivers a much deeper, louder, full-bass straight-pipe exhaust rumble.
Q: Should I buy this pipe alone, or upgrade to the complete $1,156 bundle?
A: Buy this standalone exhaust if you already own an EGR delete and CAN bus plugs. If starting from scratch, upgrade to the All-in-One Kit to get this 5" pipe bundled with a performance 3.5" downpipe, EGR delete, and 17-19 or 20-23 CAN plugs—saving you time and money.（Tuner need be purchased separatel).
Q: Does a 5" diameter add any real benefit on the L5P's factory layout?
A: On a stock truck, removing the restrictive factory DPF yields identical power gains with either a 4" or 5" system. The 5" diameter only provides a mechanical advantage once you upgrade the turbocharger and push the L5P past 500 wheel horsepower.
Q: Will a 5" exhaust hurt low-end torque on an L5P?
A: Yes, slightly. Because a 5" pipe has a larger volume, exhaust gas velocity drops at lower RPMs, which can soften off-idle throttle response on a daily driven, stock-turbo truck. However, on a built engine pushing over 3,000 RPM, the 5" pipe flows the massive air volume the engine demands.
