2017-2019 GM 6.6L L5P Duramax 4in or 5in Downpipe Back Race Exhaust


Please email us for current inventory stock at

4″ and 5″ Stainless Steel Exhaust Kits is in stock

4″ Aluminized with Muffler are OUT OF STOCK estimated restock date June 24

4″ Aluminized No Muffler Exhaust Kits are OUT OF STOCK estimated restock date July 1

5″ Aluminized No Muffler & with Muffler Exhaust Kits are in LIMITED SUPPLY



***If you are purchasing an exhaust kit and live in Alaska or Hawaii please purchase this shipping here***

In need of a full L5P race package.

4′ and 5″ Downpipe-Back DPF & CAT delete exhaust system.

Vehicle fitment – 2017, 2018 & 2019 Chevy / GMC Duramax Diesel L5P. Silverado and Sierra pickup trucks. Crew cab short bed & crew cab long bed. This will not fit the 3500/4500/5500 Cab & Chassis commercial style truck.

Exhaust Material  Available in aluminized steel or T-409 stainless steel. Aluminized steel is our most popular but will eventually accumulate surface rust. T-409 stainless steel. Unlike T-304 Stainless its still magnetic. So if your testing to see if you actually got stainless; beware that a magnet will still stick to it. We suggest the stainless upgrade if you regularly operate your truck on salted winter roads. Use drop down menu to make desired selection.

Installation – Install takes approx. 1hr with basic hand tools done on the ground of your driveway or garage. Quicker if you have automotive style lift. Cutting may be be required to fit shorter wheelbase bed/cab configurations. Clamps, hangers and hardware are included. You may have to re-use some factory hardware.

Fuel Mileage – Expect to see a significant increase in fuel mileage. If your DPF is plugged up your probably averaging about 13-14 mpg. More or less depending on the severity of the restriction. After deleting the DPF/CAT expect to get a combined mileage of 18-19 mpg. Larger tires and poor driving habits will skew mileage downward.

Tuner Required – Removal of the DPF, CAT, SCR, and/or DOC involves removing and eliminating emission related sensors. A DPF delete capable tuner is required to prevent any check engine light or diagnostic trouble codes from setting. If you don’t already have a DPF delete capable tuner we recommend Our Kit

If you need multiple exhausts add to cart separately 

*We carry stainless and aluminized, stainless ships faster. If for some reason aluminized is 2 or more weeks out we have stainless in stock and we will email you if you would like to upgrade and receive it faster.*

**If you can’t wait, need permission from your wife or will be impatient and email us for a status after 2 days, Don’t purchase. These are big boxes and we’re not amazon. You will be charged a CANCELLATION FEE of 15% for any CANCELED orders regardless of the reason.**

Customer Notification and Disclaimer of Liability. This is a race-only product. It is not legal for sale or use on pollution controlled vehicles that are driven on public streets, roads, or highways. Buyer’s use or installation of this product for itself or for Buyer’s customer is at Buyer’s own risk. The Buyer is responsible for obeying federal, state, and local laws. Only Buyer can determine end customer’s use and thus assumes any and all liability hereby waiving any and all claims against Dieselology in the sale of this product to the maximum extent permissible by law. Make sure to abide by all local, state, and federal laws, including emissions, vehicle safety, and traffic laws. It is Buyer’s responsibility to know what those laws are and how they apply to Buyer or Buyer’s customer. This product is designed and intended solely for legally-organized and sanctioned, closed- course, off-road competition use and is not for use on public streets, roads, or highways. This Product is capable of disabling the emissions system on some vehicles. Use on public streets, roads, or highways is a violation of federal and certain state (including California) and local environmental laws

Additional information

Weight 70 lbs
Dimensions 53 × 18 × 13 in




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