Description
Complete Performance Package: 3.5" Downpipe + EGR Delete Kit for 2017-2023 Duramax L5P
Transform your 2017-2023 Chevrolet Silverado or GMC Sierra 2500HD/3500HD with the 6.6L Duramax L5P Turbo Diesel using this comprehensive performance package. This kit combines two essential L5P upgrades — a 3.5" mandrel-bent turbo downpipe and a complete EGR cooler & valve delete kit — into one complete package. Address both exhaust restriction and intake contamination simultaneously for maximum performance gains and long-term engine reliability.
Package Contents
3.5" Turbo Downpipe
- T409 mandrel-bent stainless steel — maintains full 3.5" internal diameter
- V-band turbo flange for precision leak-free connection
- OEM hanger points — true bolt-on installation
- Replaces restrictive factory flattened downpipe
- 30-50% backpressure reduction at turbo outlet
EGR Cooler & Valve Delete Kit
- CNC-machined 6061-T6 billet aluminum construction
- EGR cooler block-off plates (intake + exhaust sides)
- EGR valve delete plate with OEM-spec MLS gaskets
- Coolant reroute fittings — proper flow path maintained
- Complete Grade 10.9 hardware kit included
Vehicle Compatibility
| Year |
Make |
Model |
Engine |
| 2017-2023 |
Chevrolet / GMC |
Silverado 2500HD / Sierra 2500HD |
6.6L Duramax L5P V8 Turbo Diesel |
| 2017-2023 |
Chevrolet / GMC |
Silverado 3500HD / Sierra 3500HD |
6.6L Duramax L5P V8 Turbo Diesel |
Why This Combo Package?
The L5P Duramax has two critical factory restrictions that limit performance and reliability: the pinched downpipe creating excessive turbo backpressure, and the EGR system causing progressive intake carbon fouling. Addressing either alone provides benefits, but addressing both simultaneously delivers transformative results:
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Unrestricted Exhaust Flow: 3.5" mandrel-bent downpipe eliminates the single most restrictive point in the L5P exhaust — the flattened factory downpipe.
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Clean Intake Air: EGR delete prevents carbon accumulation on intake valves, swirl flaps, and manifold — preserving airflow and power for the life of the engine.
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Synergistic Gains: Cleaner intake charge + freer exhaust flow = 25-40 HP combined potential with supporting calibration.
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Maximum Reliability: Eliminates both EGR cooler failure risk (coolant in cylinders) and high-EGT conditions caused by exhaust restriction.
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Cost-Effective: Bundle pricing saves 15-20% compared to purchasing downpipe and EGR delete kit separately.
Premium Build Quality
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T409 Stainless Steel Downpipe: Mandrel-bent for consistent internal diameter — no crush bends, no flow restrictions.
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CNC Billet 6061-T6 Aluminum EGR Plates: Precision-machined for exact L5P port matching. Anodized finish for corrosion resistance.
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MLS (Multi-Layer Steel) Gaskets: Rated for L5P boost pressures exceeding 35 PSI — no leaks, no failures.
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Grade 10.9 Mounting Hardware: High-tensile fasteners engineered for diesel vibration and thermal cycling.
Performance Benefits
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+25-40 HP / +50-80 lb-ft Torque: Combined effect of reduced backpressure and clean intake air with proper tuning.
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100-200°F Lower EGTs: Critical safety improvement for towing heavy loads up long grades.
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Faster Turbo Spool: Immediate throttle response improvement from reduced exhaust restriction.
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Eliminated Carbon Buildup: No more EGR soot fouling intake valves and manifold — preserved airflow forever.
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No Coolant Loss Risk: EGR cooler failure permanently eliminated — protects head gaskets and rotating assembly.
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1-3 MPG Fuel Economy Gain: Combined efficiency improvement from both modifications.
Installation Overview
This comprehensive package requires significant disassembly — the downpipe is accessed from underneath, while EGR delete requires intake manifold removal from above. Estimated total installation time: 8-12 hours. Professional installation strongly recommended. Compatible tuning solution required for EGR delete function. All necessary hardware, gaskets, clamps, and fittings are included. No welding or permanent modifications needed.
Frequently Asked Questions
Q: Will this fit my 2020 Silverado 3500HD L5P?
A: Yes. This combo kit fits all 2017-2023 Chevrolet Silverado 2500HD/3500HD and GMC Sierra 2500HD/3500HD with the 6.6L Duramax L5P engine. All cab and bed configurations supported.
Q: Do I need a tuner with this kit?
A: Yes. A compatible tuning solution is required to disable EGR-related DTCs and optimize engine parameters for the modified exhaust and intake configuration. For maximum performance benefit, a comprehensive tune addressing both modifications is recommended.
Q: Can the downpipe and EGR delete be installed at different times?
A: Yes, each component can be installed independently. However, installing both simultaneously saves significant labor time since the intake removal (for EGR) and under-vehicle access (for downpipe) involve related disassembly steps. Most shops recommend doing both at once.
Q: Is this kit reversible?
A: Both the downpipe and EGR delete kit are bolt-on designs with no cutting, welding, or permanent modifications. The factory components can be reinstalled. Tuning will need to be restored to stock as well.
Q: How does this compare to buying the downpipe and EGR delete separately?
A: The combo kit provides identical components at a bundled price — typically 15-20% savings versus purchasing individually. All hardware, gaskets, and fittings are identical to the standalone kits.
Q: Will I need a wheel alignment after installation?
A: No — neither the downpipe nor the EGR delete kit affect suspension geometry. A wheel alignment is not required.
Q: Is this product intended for on-road use?
A: This product is designed for off-road and competition use only. Not intended for vehicles subject to emissions regulations. Check local and state laws before purchase.
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⚠️ Off-Road / Competition Use Only: This product is intended for off-road or competition vehicles only. Not legal for highway use on emissions-controlled vehicles in the US and many other jurisdictions. Check local and federal regulations before purchasing. Removal of emissions equipment may void your vehicle warranty.
