SPDZ1 3.5" Downpipe Exhaust – 2017–2025 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 2017–2025 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: 2017–2025 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.