SPDZ1 2017-2023 6.6L Chevy L5P Duramax Diesel 3.5" Downpipe Exhaust (PreOrder)
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*** Market Conditions after 2020 have changed the landscape of automotive parts. Although we try to stock 1000's of items in our multiple warehouse and use multiple distribution channels, having back-orders are unavoidable in today's market. If you are in need of a product quickly, we suggest email, message, or call us for availability so that we may explore your options.
Email: Sales@Speedzoneweb.com
Call: 407-846-8430
Text: 407-749-6314
Frequently Asked Questions
SKU: SZY-042-CATLESS
SPDZ1 3.5" Downpipe Exhaust – 2017–2023 Chevy/GMC 6.6L L5P Duramax
Unleash the true power of your L5P Duramax with the SPDZ1 3.5" Downpipe Exhaust, engineered for maximum flow, durability, and performance. Designed specifically for the 2017–2023 Chevy Silverado & GMC Sierra 2500HD/3500HD 6.6L Duramax (non–Cab & Chassis), this upgrade replaces the restrictive factory downpipe with a free-flowing 3.5” stainless steel system built to handle serious power.
By eliminating the factory DOC and improving exhaust velocity by up to 20% more flow than stock, the SPDZ1 downpipe helps your turbo breathe easier—delivering more horsepower, torque, quicker spool-up, and lower EGTs. Built with high-quality stainless steel, a 4-bolt flange with pre-installed studs, and a precision sealing ring, this downpipe ensures leak-free reliability even under heavy towing or track conditions.
Key Features:
✅ Fitment: 2017–2023 Chevrolet Silverado & GMC Sierra 2500HD / 3500HD (6.6L L5P Duramax, excludes Cab & Chassis models)
✅ Performance: 20% better exhaust flow than factory downpipe for more power & efficiency
✅ Material: Premium stainless steel, corrosion-resistant and built to last
✅ Design: 3.5” mandrel-bent tubing with 4-bolt flange & two pre-installed studs
✅ Reliability: Includes high-quality sealing ring to prevent leaks
✅ Power Gains: Faster turbo spool, reduced EGTs, and improved towing performance
✅ Installation: Direct bolt-on design, quality tested for durability and trouble-free fitment
Built to the SPDZ1 Racing Standard, this downpipe is the perfect balance of power, sound, and reliability—giving your Duramax the aggressive edge it deserves whether on the street, track, or hauling heavy loads.
***** This is a Pre-Order Item, we expect to ship to customers in the 3rd week of September 2025 ********
Our History
For 23 years Speedzone Performance LLC has been providing aftermarket car parts to Central Floridians and 1000's of customers online. What makes us different than all the other places online? We have 3 actual brick and mortar locations where were serve customers daily and find new ways to provide support and assistance to the automotive community at large. From our in house SPDZ1 Brand, to our constantly growing in stock inventory, we strive to make our customer service and ease of purchase stand out from the rest! We are also one of the largest automotive part financing providers anywhere in the United States, and continue to provide more options for our customers every year. We love what we do, and it shows in every product we sell and every new customer who becomes a part of our Speedzone Family.