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 6.6L Duramax L5P engine feature a massive, highly restrictive emissions assembly that traps extreme thermal heat and causes frequent active regens. As these work trucks age, failure of DEF pumps, heaters, and NOx sensors routinely leads to costly dealer repairs and triggers speed-restricting Limp Mode countdowns.
- The 5" L5P Downpipe-Back Exhaust replace the entire underbody system downstream of the front downpipe, this kit removes all factory emissions bottlenecks and replaces tired, rusted tailpipes. By reducing system backpressure to near zero, it sharply lowers towing EGTs, restores sharp throttle response, improves fuel economy, and unleashes an aggressive V8 diesel roar.
Key Features
- Heavy-Duty Material: Mandrel-bent 5" T409 stainless steel tubing built to withstand intense exhaust temperatures, road debris, and harsh winter road salt without rusting.
- Sharply Drop Towing EGTs: Flushes out trapped exhaust thermal heat right behind the front downpipe, allowing scorching exhaust gases to exit rapidly to protect engine during heavy towing.
- Restore Deep Diesel V8 Sound: Removes all restrictive factory emissions baffles to deliver a clean, aggressive diesel V8 tone and fast turbo spool-up whistle.
- Permanently Bypass DEF & Limp-Mode Errors: Eliminates failure-prone L5P DEF injectors, pumps, heaters, and NOx sensors that trigger automatic 55-MPH dealer Limp Mode lockouts.
- Full Downpipe-Back Exhaust: Replaces the heavy, choked OEM DPF, CAT, SCR, and stock rear tailpipe with a seamless 5" high-flow exhaust from the downpipe outlet to the tailpipe exit.
FAQ
Q: What is the main difference in sound and performance between a 4" and 5" Downpipe-Back kit on an L5P?
A: 4" pipe is easier to install, preserves low-end exhaust velocity for daily street tunes, and retains a tighter chassis fit. A 5" full system is built for high-horsepower setups seeking maximum flow, lowest EGTs, and a much louder, deeper V8 rumble.
Q: Will this 5" full exhaust pipe fit under my L5P truck without hitting the rear axle or spare tire?
A: Yes. The rear axle over-bend and extension pipes are CNC mandrel-bent to precisely follow GM's OEM exhaust clearance paths, leaving safe clearance around the transmission crossmember, rear axle, shock absorbers, and factory spare tire.
Q: Does this kit replace the front downpipe off the turbocharger?
A: No. This is a Downpipe-Back system, meaning it bolts directly to the outlet connection of your stock front downpipe. It replaces all exhaust piping downstream from that point to the rear exit.
Q: Do I need to reinstall factory DEF or EGT sensors into this pipe?
A: No. This is a smooth, bungless straight-pipe design. Once your L5P ECM is flashed with a custom tune, all emissions sensors are electronically deactivated—simply unplug the harnesses and zip-tie them securely to the frame.
