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Dyno-Proven Tri-Y Exhaust Upgrade for the 2022 through 2025 Chevrolet C8 Corvette Z06 LT6 5.5L
The Kooks 2181HY30 is a 1-7/8 inch by 2 inch stepped Tri-Y long tube header and Ultra GREEN catted connection kit purpose-built for the flat-plane crank LT6 5.5L V8 in the C8 Corvette Z06. Unlike traditional 4-into-1 designs, the Tri-Y architecture pairs cylinders in the optimal firing order sequence before merging into secondary collectors, which dramatically reduces exhaust pulse interference and unlocks additional horsepower and torque at mid to high RPM where the LT6 thrives.
Every tube is mandrel-bent T304 aircraft-quality stainless steel with 3/8 inch laser-cut flanges and hand-ported inlets that match the LT6 cylinder head port dimensions precisely. The included Ultra GREEN catted connection pipes use 5-inch bodied 300 CPSI high-output catalytic converters rated for forced induction applications up to 1,000 wheel horsepower, so the 2181HY30 remains emissions-compliant in all 49 non-CARB states while delivering a full-throttle sound and power character that stock manifolds physically cannot achieve.
Kooks engineers developed the 2181HY30 specifically around the LT6 firing order, bore spacing, and collector geometry to maximize exhaust scavenging across the entire RPM range of the 8,600 RPM redline. The stepped tube design transitions from 1-7/8 inch primaries into 2 inch secondaries before merging, maintaining velocity while increasing volume at the precise point where the LT6 demands it. Flanged connection pipe outlets bolt directly to the OEM axle-back system without cutting or welding, preserving factory rear exhaust aesthetics and simplifying the installation significantly. A tune is required after installation to optimize air/fuel ratios for the improved exhaust flow. California residents: this product does not meet CARB standards and is not legal for street use in California.
Key Features
- Stepped Tri-Y Design: 1-7/8 inch to 2 inch stepped tubes paired by LT6 firing order for superior scavenging at mid and high RPM.
- Ultra GREEN Catted Connection Pipes: 5-inch bodied 300 CPSI high-output catalysts rated to 1,000 WHP, connecting directly to the OEM axle-back.
- T304 Aircraft-Quality Stainless Steel: 16-gauge mandrel-bent tubing with full TIG welds resists heat, corrosion, and cracking through years of hard use.
- 3/8 Inch Laser-Cut Flanges: Hand-ported inlets match the LT6 port geometry for a leak-free seal that eliminates gasket blowout.
- OEM Axle-Back Compatible: Flanged outlets connect directly to the factory rear exhaust without cutting, welding, or fabrication.
- 49-State EPA Compliant: Ultra GREEN catalysts meet federal emissions requirements outside California CARB jurisdiction.
- Tune Required: ECU recalibration is required after installation to optimize air/fuel ratios for peak power.
- Made in the USA: Each 2181HY30 is hand-crafted to order at Kooks' American facility.
What's Included
- Left and right 1-7/8 inch x 2 inch stepped Tri-Y T304 stainless steel headers
- Pair of Ultra GREEN 3 inch x OEM flanged catted connection pipes with 5-inch 300 CPSI catalysts
- Stage 8 locking header bolts and mounting hardware
- Exhaust port gaskets
- O2 sensor extensions and retainers
- Clamps and hangers
Installation Instructions
Installation of the Kooks 2181HY30 requires lifting and safely supporting the vehicle on jack stands or a lift. Remove the factory exhaust manifolds from both cylinder banks after disconnecting the oxygen sensor harnesses. Position the new Tri-Y headers against the cylinder head ports and thread the included Stage 8 locking bolts by hand before torquing to specification in the sequence outlined in the included instruction sheet. Route the catted connection pipes from the header collectors to the OEM axle-back flanges and secure with the included clamps. Reconnect O2 sensors using the provided extension harnesses. A professional ECU tune is required following installation to achieve proper air/fuel ratios and maximize the power gains the 2181HY30 delivers. Professional installation is recommended given the complexity of header swaps on the mid-engine C8 platform.
Product Specifications
| Specification | Detail |
|---|---|
| Manufacturer Part Number (MPN) | 2181HY30 |
| UPC | 842422181659 |
| Header Type | Tri-Y Long Tube |
| Primary Tube Diameter | 1-7/8 inch (stepped to 2 inch) |
| Connection Pipe Diameter | 3 inch |
| Catalyst Type | Ultra GREEN 300 CPSI High-Output, 5-inch body |
| Max Supported Power | Up to 1,000 WHP (with forced induction) |
| Flange Thickness | 3/8 inch laser-cut |
| Material | T304 Aircraft-Quality Stainless Steel |
| Wall Gauge | 16 Gauge |
| Finish | Natural Stainless Steel |
| Connection Style | Flanged outlet to OEM axle-back |
| Tune Required | Yes |
| Emissions Compliance | 49-State EPA Compliant (Non-CARB) |
| Country of Manufacture | USA |
| Lead Time | Typically 4 to 6 weeks (built to order) |
| Warranty | Limited Lifetime on stainless components; 25,000 miles on catalysts |
This Part Fits
| Year | Make | Model | Submodel | Engine |
|---|---|---|---|---|
| 2023 | Chevrolet | Corvette | Z06 | 5.5L LT6 V8 |
| 2024 | Chevrolet | Corvette | Z06 | 5.5L LT6 V8 |
| 2025 | Chevrolet | Corvette | Z06 | 5.5L LT6 V8 |
Frequently Asked Questions
Does the Kooks 2181HY30 require a tune?
Yes. A professional ECU tune is required after installing the 2181HY30 to correct air/fuel ratios for the improved exhaust flow. Running without a tune will result in check engine lights and suboptimal performance.
Will the 2181HY30 throw a check engine light?
Without a tune, yes. After a proper tune using the Ultra GREEN catalysts, the system operates without triggering CEL codes in most cases. Results depend on the specific tune and ECU software version.
Does the Kooks 2181HY30 connect to the factory axle-back exhaust?
Yes. The flanged connection pipe outlets bolt directly to the OEM axle-back system with no cutting, welding, or fabrication required.
Is the Kooks 2181HY30 legal in California?
No. The 2181HY30 does not meet California Air Resources Board (CARB) standards and is not legal for street use in California or other CARB-regulated states. It is 49-state EPA compliant.
How much horsepower does the Kooks 2181HY30 add to a C8 Z06?
Actual gains vary by tune, supporting modifications, and driving conditions. The Tri-Y design and reduced restriction are proven to increase horsepower and torque, particularly at mid to high RPM where the LT6 flat-plane crank revs hardest.
How long does it take to get the Kooks 2181HY30?
The 2181HY30 is built to order at Kooks' USA facility. Lead time is typically 4 to 6 weeks from the order date.
What is the warranty on the Kooks 2181HY30?
Kooks provides a limited lifetime warranty on the stainless steel header components and a 25,000-mile warranty on the catalytic converters in the connection pipes.
Does the Kooks 2181HY30 fit the Corvette Z06 with the Z07 Performance Package?
Yes. The 2181HY30 is compatible with 2023 to 2025 Chevrolet C8 Corvette Z06 in all configurations including Z07-equipped vehicles, as the headers replace the factory exhaust manifolds which are identical across Z06 trim levels.
Can I use my factory oxygen sensors with the 2181HY30?
Yes. The included O2 sensor extension harnesses reposition the factory oxygen sensors correctly within the new header routing so no sensor replacement is required.
Prop 65 Warning
WARNING: This product can expose you to chemicals including Chromium and Nickel, which are known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information, visit www.p65warnings.ca.gov.
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