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 4" 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 4" 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 your turbo and 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 4" high-flow exhaust from the downpipe outlet to the tailpipe exit.
FAQ
Q: What is the difference between a Mid-Pipe Delete and this Downpipe-Back kit?
A: A mid-pipe delete only replaces the DPF/SCR canisters under the cab while forcing you to keep your stock rear tailpipe. This Downpipe-Back Kit replaces everything from the front downpipe outlet all the way to the rear bumper exit, giving you maximum airflow and a fresh tailpipe section.
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: Will this 4" Downpipe-Back kit fit both Short Bed and Long Bed trucks?
A: Yes. The kit includes modular extension pipe sections designed to fit all cab and bed lengths. You simply trim the straight extension pipe section during installation based on your specific wheelbase.
Q: Do I need a custom ECM tune to run this 4" Downpipe-Back exhaust?
A: Yes. The 2017+ L5P requires an ECM unlock and custom delete tuning to disable active regens, DEF system components, and NOx sensors. Installing this pipe without a custom tune will immediately trigger check engine lights and limp mode.
