Know the landed cost before you order
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Finish your C7 header upgrade with the sound you want
The X-pipe is more than a connection between your headers and rear exhaust. It is part of the sound and catalyst specification you choose for your Corvette. These Kooks stainless packages offer conventional X-pipe and ULTRA X-pipe layouts, with front connections and a 2-3/4" OEM rear connection for the listed C7 applications.
SKUs: 21703100, 21703120, 21703220, 21703300, 21703320, 21703400, 21703420
Choose the crossover character
The conventional X-pipe joins the two exhaust streams through a crossover. The ULTRA X-pipe uses a longer merge, combining a smooth exhaust character with a deeper muscle-car note. Choose the layout with your rear mufflers in mind; the finished sound comes from the whole system.
Choose catalysts for your engine
Performance Cats are for naturally aspirated LT1 builds up to 550 RWHP. GREEN, H.O. GREEN and their different substrate and body specifications give naturally aspirated and forced-induction builds further choices. H.O. GREEN uses a 4-1/2" body with 300 CPSI substrate, while GREEN uses a 4" body and 400 CPSI substrate. Competition Only options provide catalyst-free pipes for a dedicated competition exhaust.
Keep a compatible OEM rear exhaust
These packages use 3" pipework with a 2-3/4" OEM rear connection and require matching Kooks long tube headers. They include the front connection arrangement and mid-pipes. They are not an X-pipe replacement for factory exhaust manifolds.
Match the engine as well as the crossover
The conventional X-pipe options cover LT1, LT4 and LT5 applications. The ULTRA Competition, GREEN and H.O. GREEN options cover LT1 and LT4. Performance-catalyst SKU 21703220 is for naturally aspirated LT1 applications. Choose by the engine and SKU, especially for a ZR1. Have the installer check belly-pan and clamp-stud clearance and recheck fasteners after the first heat cycle.
Choose your option
| SKU | Merge Style | Cats | Fitting / contents | Stated use restriction |
|---|---|---|---|---|
| 21703100 | X Pipe | Comp. Only | Conventional X-pipe; LT1/LT4/LT5; 2-3/4" OEM rear outlet. | Competition, off-road and track use only. Not for use on public roads. Kooks competition-use waiver required. |
| 21703120 | ULTRA X | Comp. Only | ULTRA long-merge X-pipe; LT1/LT4; 2-3/4" OEM rear outlet. | Competition, off-road and track use only. Not for use on public roads. Kooks competition-use waiver required. |
| 21703220 | ULTRA X | Performance Cats | ULTRA long-merge X-pipe; naturally aspirated LT1 applications up to 550 RWHP; 2-3/4" OEM rear outlet. | |
| 21703300 | X Pipe | GREEN Cats | Conventional X-pipe; LT1/LT4/LT5; 2-3/4" OEM rear outlet. | |
| 21703320 | ULTRA X | GREEN Cats | ULTRA long-merge X-pipe; LT1/LT4; 2-3/4" OEM rear outlet. | |
| 21703400 | X Pipe | H.O. GREEN Cats | Conventional X-pipe; LT1/LT4/LT5; 2-3/4" OEM rear outlet. | |
| 21703420 | ULTRA X | H.O. GREEN Cats | ULTRA long-merge X-pipe; LT1/LT4; 2-3/4" OEM rear outlet. |
Vehicle fitment
| Years | Vehicle and trim | Engine | Applicable SKU / fitting conditions |
|---|---|---|---|
| 2014-2019 | Chevrolet Corvette Stingray | 6.2L V8 | 21703100, 21703120, 21703220, 21703300, 21703320, 21703400, 21703420 |
| 2014-2016 | Chevrolet Corvette Z51 | 6.2L V8 | 21703100, 21703120, 21703220, 21703300, 21703320, 21703400, 21703420 |
| 2015-2019 | Chevrolet Corvette Z06 | 6.2L V8 | 21703100, 21703120, 21703300, 21703320, 21703400, 21703420. Performance-catalyst 21703220 is for naturally aspirated builds, not the supercharged LT4 |
| 2017-2019 | Chevrolet Corvette Grand Sport | 6.2L V8 | 21703100, 21703120, 21703220, 21703300, 21703320, 21703400, 21703420 |
| 2019 | Chevrolet Corvette ZR1 | 6.2L V8 | 21703100, 21703300, 21703400. Conventional X-pipe options only; ULTRA options cover LT1/LT4 |
Ordering and delivery
Estimated lead time is 4-6 weeks. Delivery may be faster depending on stock levels. Shipping is charged separately.
Technical specifications
| Specification | Details |
|---|---|
| Application | Corvette C7, 2014-2019; exact engine scope shown by SKU |
| Construction | 304 stainless steel; ULTRA X-pipe uses a long-merge crossover |
| Pipe diameter | 3" pipework |
| Rear connection | 2-3/4" OEM rear-exhaust connection |
| Supplied exhaust parts | X-pipe arrangement with front connections and mid-pipes |
| Required headers | Matching Kooks long tube headers, purchased separately |
| Performance catalyst limit | Naturally aspirated LT1 engines, up to 550 RWHP |
| Fitting detail | Check belly-pan clearance; clamp studs may need trimming |
Frequently asked questions
Will it fit the factory manifolds?
No. This is the connection and X-pipe arrangement for matching Kooks long tube headers.
Does every ULTRA version fit an LT5 ZR1?
For an LT5 ZR1, choose conventional X-pipe 21703100, 21703300 or 21703400. The ULTRA Competition, GREEN and H.O. GREEN choices here cover LT1/LT4; Performance-catalyst 21703220 is for naturally aspirated LT1 applications.
Can I keep the original rear exhaust?
Yes, using the compatible 2-3/4" OEM rear connection.
Is ULTRA X-pipe the same thing as ULTRA-GREEN?
No. ULTRA X-pipe describes the crossover layout. ULTRA-GREEN is a catalyst type, and is not an offered catalyst option on this page.
