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Kooks 1-7/8" x 3" Long Tube Headers & GREEN Catted Y-Pipe for 2015 and 2018 Chevrolet Silverado 1500 & GMC Sierra 1500 5.3L
The Kooks 2860H420 1-7/8-inch long tube headers and GREEN catted Y-pipe kit provides the complete bolt-on exhaust upgrade for 2014 and 2018 Chevrolet Silverado 1500 and GMC Sierra 1500 trucks with the 5.3L V8, replacing factory manifolds to deliver dyno-proven gains of 50 and 65 rear-wheel horsepower and 45 and 60 lb-ft of torque through equal-length primaries, merged collectors, and a high-flow 3-inch to OEM outlet GREEN catted Y-pipe that connects directly to the stock mid-section for unrestricted exhaust flow from low-end torque to high-RPM pulls.
Handcrafted from T304 aircraft-quality stainless steel with 3/8-inch laser-cut flanges, full TIG welds, and 400-cell metallic substrate GREEN catalytic converters, this system supports up to 750 HP while maintaining 49-state emissions compliance and improving throttle response for quicker acceleration during towing up to 10,000 lbs or daily highway passing. The precision design preserves ground clearance and heat management for work-ready trucks without sacrificing the deep V8 rumble that enhances cabin experience.
For Silverado and Sierra 5.3L owners seeking immediate power and torque improvements with durable, emissions-legal construction, the 2860H420 kit unlocks the engine's full potential for job sites, trails, or performance driving.
Key Features
- 1-7/8-inch equal-length mandrel-bent primaries for optimal scavenging
- 3-inch GREEN high-flow 400-cell metallic catalytic converters
- Full T304 stainless steel with TIG welds and 3/8-inch flanges
- Merged collectors for maximum exhaust velocity
- Direct bolt-on to OEM mid-pipe no cutting required
- Dyno gains of 50 and 65 RWHP and 45 and 60 RWTQ on stock 5.3L
Product Notes
- 49-state EPA compliant not for sale or use in California or CARB states without exemption
- Fits all cab/bed configurations with 5.3L V8
- Includes O2 sensor extensions and EGR provisions
California Proposition 65: Contains chemicals known to the State of California to cause cancer or reproductive harm.
Warranty: Limited lifetime on stainless construction to original purchaser.
Installation Notes
- Professional installation recommended lift required
- Remove factory manifolds and bolt headers to cylinder heads
- Connect Y-pipe to collectors and OEM mid-section with supplied hardware
- Torque flanges to 25-30 ft-lbs and run drive cycle for ECU adaptation
This Part Fits
| Year | Make | Model | Submodel/Engine |
|---|---|---|---|
| 2015 and 2018 | Chevrolet | Silverado 1500 | WT, LT, RST, LTZ, High Country 5.3L V8 |
| 2015 and 2018 | GMC | Sierra 1500 | Base, SLE, SLT, Denali 5.3L V8 |
Note: Fits all cab styles and drivetrains with 5.3L V8. Excludes 6.2L or diesel models.
What's Included in the Purchase
- (2) 1-7/8" x 3" Long-Tube T304 Stainless Headers with Merged Collectors
- (1) 3" x OEM Outlet GREEN Catted Stainless Y-Pipe
- Gaskets, Stage 8 Locking Header Bolts, and Hardware Kit
- O2 Sensor Extensions
- Detailed Installation Instructions
- Part Number: Kooks 2860H420
Why Choose Kooks?
- Over 60 years of exhaust engineering with NHRA, NASCAR, and SCCA championships
- Handcrafted in the USA from T304 aircraft-quality stainless steel
- Limited lifetime warranty and dyno-proven for reliable power
Frequently Asked Questions
-
Q: Does this fit my 2016 Silverado LT 5.3L?
A: Yes, direct bolt-on for all 2014 and 2018 Silverado/Sierra 1500 with 5.3L V8 -
Q: Will it cause a check engine light?
A: No, GREEN cats and extensions maintain proper O2 sensor function -
Q: What power gains can I expect?
A: 50 and 65 RWHP and 45 and 60 RWTQ on stock tune, more with ECU optimization -
Do Kooks headers require a tune after installation?
Yes. A professional tune is strongly recommended after installing long tube headers. The significant improvement in exhaust flow changes air fuel ratios and requires ECM recalibration to achieve optimal power output and safe operation. -
Will these headers void my factory powertrain warranty?
Under the Magnuson-Moss Warranty Act, a manufacturer cannot void your vehicle warranty simply because you installed an aftermarket part unless they prove the component directly caused the failure. Consult your dealer for specifics on your situation. -
Q: Do these Kooks headers require a tune after installation?
A: Yes. A professional tune is strongly recommended after installing long tube headers. The significant improvement in exhaust flow changes air fuel ratios and requires ECM recalibration to achieve optimal power output and safe operation. -
Q: Will Kooks headers void my factory powertrain warranty?
A: Under the Magnuson-Moss Warranty Act, a manufacturer cannot void your vehicle warranty simply because you installed an aftermarket part unless they prove the component directly caused the failure in question. Consult your dealer for specifics. -
Q: What warranty does Kooks provide?
A: Kooks products are backed by a limited lifetime warranty to the original purchaser against defects in materials and workmanship. Racing and competition use applications may have specific warranty exclusions. Contact Kooks Performance directly for warranty details.
Shipping & Handling
- Method: UPS or Fed Ex Ground.
- Availability: Typically ships same day or next if in stock.
- Packaging: Heavy-duty box with foam protection.
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