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Attention: You are purchasing closed course competition Product(s)

I acknowledge that the product(s) being purchased () was/were designed and intended for closed course competition use only. The product(s) is/are neither designed nor intended for use on public roads or land and is against Federal and State regulations to do so. By proceeding with this purchase, I , agree to only use the product(s) for closed course competition.

If an ECU tune was purchased, please send your unmodified and undamaged OEM ECU to TST Industries, located at 623 Pleasant St, Lake Helen, FL 32744.

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FREE SHIPPING OPTION FOR DOMESTIC ORDERS:

U.S. customers are offered a free shipping option for orders with a discounted subtotal greater than $150.00 (before taxes applied). The order's shipment destination must reside within the United States of America. The free shipping options still utilize our standard postage providers and 3rd party shipping companies. Does not apply to large items such as exhausts, stands, and bodywork shipping. All terms and conditions that apply to normal orders will continue to apply to orders with a free shipping option.

NO RESTOCKING FEES:

An item returned within 30 days of purchase, that includes an accurate RMA#, in a perfectly new, unopened condition, and that complies with our other return policies, will not be charged a restocking fee.

MOST QUESTIONS ABOUT THIS PRODUCT CAN BE ANSWERED ON THIS PAGE.

The most common product related questions are answered in the tabs section on this page. Be sure to carefully read through the "Product Details", "In the Box", and "FAQs" tabs. In addition, a lot of our products have comprehensive videos demonstrating installations and product features. You can find those videos in the "Videos" tab.

Note: Some product pages may not have all the tabs mentioned above. Please read through all the available tabs to find the answers to your questions. If you still need assistance, please use the "ASK A QUESTION ABOUT THIS PRODUCT" button below the tabs section.
NO ADDITIONAL COST: You pay at the time of checkout and never have to worry again.
COVERAGE: Our Limited Extended Warranty starts on the date of purchase. It covers all manufacturer defects for our TST Exclusive products. (Products manufactured by us with the exception of our WORX products)
EXPERT HELP: As always our team is here to help. If you’re unsure about this warranty or if your product is eligible, feel free to reach out to us and we can help answer any questions you may have!
PRODUCT ELIGIBILITY: TST will offer our Limited Extended Warranty on all products manufactured by TST Industries.
EASY CLAIMS PROCESS: Simply click the “Contact Us” page and fill out the “Returns Form” to begin the warranty process. Once our team receives your email and initiates the RMA, you can send your product back to us and we will repair/replace the product at no cost as long as a manufacturer defect is found. What qualifies as a manufacturer defect? Check out our Terms and Conditions for some examples!

TST WORX Airbox for Kawasaki Ninja 400 2018-2023

  • TST WORX Airbox for Kawasaki Ninja 400 2018-2023
  • TST WORX Airbox for Kawasaki Ninja 400 2018+ for Non-ABS Models.
  • What's included in the TST WORX Airbox.
  • ABS Compatible TST WORX Airbox for Kawasaki Ninja 400 2018-2023.
  • Developed by the TST WORX Race Team Engineers and thoroughly tested on track.
  • Pre-installed V2 Velocity Stacks optimize volumetric efficiency for better top-end performance.
  • Engineered to deliver more airflow to the Kawasaki 399cc engine.
  • Unique mounting brackets with red anodized hardware for a total WORX design.
  • Improves top-end power delivery.
  • Provides a 5.5% increase to area under the curve when paired with the WORX Stage 3 Tune.
  • Improve the top end power of your Kawasaki Ninja 400 with the TST WORX Airbox.

TST WORX Airbox for Kawasaki Ninja 400 2018-2023

TST WORX Airbox for Kawasaki Ninja 400 2018-2023

Upgrade to podium-worthy performance with the TST WORX Airbox. Built from updated premium materials and hand-assembled in our Florida facility, this race-tuned kit includes our exclusive Airbox, Air Filter, and V2 Velocity Stacks that combine to enhance airflow and top-end performance, helping you achieve faster lap times and race day dominance—all at a new, lower price.

Add the tune to ensure your ECU is optimized for the enhanced airflow. Send us a stock, untuned, undamaged, and unmodified Ninja 400 ECU, and we'll flash it with our Stage 3 Tune. For best results, consult a tech who specializes in high-performance race bike tuning. See the Tune Details tab for more info.

This item is not eligible for discounts.

Applications:

Kawasaki Ninja 400 | 2018, 2019, 2020, 2021, 2022, 2023

This product is part of our Worx Program!

Learn More!
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SKU
2018 - 2023/Ninja 400/Kawasaki
TST WORX Airbox for Kawasaki Ninja 400 2018-2023
 
Price: $599.99
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ATTENTION:

If buying this product as part of the Buy Together bundle below, define these options there.

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CLOSED COURSE APPLICATIONS ONLY
This airbox was designed and intended for closed-course competition use ONLY. This product is neither designed nor intended for use on public roads or land and it is against Federal and State regulations to do so.

  • Product Details
  • Tune Details
  • What's Included
  • Recommended Accessories
  • FAQs

Product Feature Episode

Installation

 

Features

  • Replaces the entire stock airbox with a race-developed design
  • 2.5 lbs lighter than the stock setup
  • Bolt-on component - no modification required*
  • Provides 8% increase to peak power compared to stock airbox
  • Provides 5-10% increase in the upper range (9500 - 12500 RPM) compared to stock airbox
  • Carbon fiber and high-strength polymer construction
  • Toray Carbon Fiber Prepreg features a high gloss clear coat for UV protection
  • Includes WORX V2 Velocity Stacks for optimized top end performance
  • Includes specific WORX developed reusable pre-oiled foam air filter
  • Comes pre-assembled and ready for installation
  • Non-ABS and ABS-Compatible versions available

*Small tab located on the frame needs to be bent to provide proper clearance for installation.

Description

Our quest for class domination led our engineers to completely redesign the airbox assembly, seeking top-end power gains through a sophisticated new design that combines with our WORX V2 Velocity Stacks and a proprietary reusable open-cell high-performance foam air filter to deliver a 5-10% increase in the 9500-12500 RPM range. When paired with our WORX Stage 3 ECU tune, or your own custom tune, the results are instantly noticeable. The WORX Airbox completely replaces the stock setup, including the stock air filter and velocity stacks, and replaces them with specifically designed components that take advantage of the improved airflow and further optimize the volumetric efficiency for better engine performance and faster lap times. Built with uncompromising quality, this Ninja 400 Airbox is unlike anything else on the market.

Already purchase a WORX Ninja 400 Tune and want to upgrade? We'll provide a free tune reflash if you've already purchased a Stage I or Stage II tune from us before and can send in the same ECU. See the Tune Details tab for more information or CLICK HERE to get the free reflash.

The WORX Airbox comes pre-assembled, therefore we are not able to substitute items or customize the airbox or velocity stacks per order.

This item is not eligible for discounts.

Tune Features

  • Stage 3 WORX Tune developed for the following:
  • Provides 5.5% increase in area under the curve
  • Increased rev limit of 12,500 RPM
  • Eliminates OEM air injection system (AIS)
  • Eliminates factory closed loop O2 system
  • Eliminates fuel injector deceleration cut for easier corner entry and braking
  • Remapped fuel tables for cylinders 1 and 2 separately across multiple throttle openings enable a smooth power delivery
  • Remapped ignition timing helps torque production and throttle response
  • Eliminates EVAP system error code after system removal
  • Eliminates gearing fault code when drive chain gear ratios are changed to non-OEM configurations
  • Disables top speed limiter
  • Available for non-ABS and ABS-equipped models

Requirements

It is your responsibility to ship an undamaged and unmodified 2018-2023 Ninja 400 OEM ECU to our facility in Lake Helen, Florida for tuning. The ECU must be properly packed and free of any damage or contaminants to be tuned properly. Once the ECU is tuned, we'll ship your newly flashed ECU back to you for installation. Please note that if your "Check Engine" light is on previous to an ECU tune, the light may remain on after the reflash and will need to be cleared manually.

If your ECU does not meet the requirements required to be flashed, we will not be able to perform the programming required to take full advantage of the other components in this bundle. It is your responsibility to confirm that your ECU is unmodified and undamaged before purchasing.

If you have an ECU that has been previously flashed with a TST WORX tune and want to upgrade your Ninja 400 with this airbox, please CLICK HERE to add a free reflash tune to your cart.

  • (1) TST WORX Airbox
  • (1) TST WORX Air Filter
  • (1) Set of TST WORX V2 Velocity Stacks
  • Necessary installation hardware

*Airbox, Air Filter, and V2 Velocity Stacks come pre-assembled for ease of installation on your Kawasaki Ninja 400.

Q: Do I have to do any modification to my bike or airbox?
A: There is a small tab that is attached to the frame that will need to be either bent or removed entirely, depending on your preference. On non-ABS models, this tab is not used for anything and is typically removed by most racers. No modification is required to the stock airbox as this is a complete replacement of the airbox assembly.

Q: Can I use a stock air filter or other aftermarket air filters with this airbox?
A: The air filter that is included with this airbox has been specifically designed to fit within the reshaped design. The stock air filter or any other aftermarket filter that has been designed for the stock airbox will not fit.

Q: How often do I need to clean or replace the air filter?
A: We recommend checking the air filter for visible debris after each race weekend. You can clean and wash the open cell foam filter and re-oil it with your preferred filter oil. If you decide you need a replacement filter, click HERE to order a new one.

Q: If I already have a WORX Tune on my Ninja 400 ECU, can I get the Stage 3 Tune at a discount?
A: Absolutely! We actually offer a free reflash of any previously tuned ECU right HERE. Just pay the $15 shipping and input the original WORX Tune order number and we'll get your ECU reflashed so you can take full advantage of the improved airflow.

Q: How long will it take for me to receive this once I order it?
A: Our handling time is 1-2 business days, and the shipping time varies based on the shipping method selected. To learn more about shipping times, please see the articles in our Terms & Conditions regarding domestic and international shipping here.

Q: I'm located outside of the United States. Will I have to pay duties on this item?
A: Some countries charge additional fees when a package is imported and delivered to the recipient. We have no way of knowing or estimating what these fees will be. It is the buyer's responsibility to cover these additional costs.

Q: What is your return and warranty policy?
A: Please read over our policies thoroughly on our terms and conditions page BEFORE making your purchase.
TST Industries Terms and Conditions
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Reviews

Customer Reviews:

Average customer rating:
 
(3 reviews)  
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3 Most useful customer reviews (see all reviews):
Perkins Racing
Jul 29, 2022
I purchased this from TST during their testing phase and I am impressed. Awesome sound, makes really good power, easy install. A work of art.

Advantages: The best

Disadvantages: Worth it
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Tom McMasters
Jul 21, 2022
This was 100% worth it and it looks wicked awesome too. I absolutely went faster at my track day weekend when I tested it out compared to my times on day 1, I dropped almost 3 seconds on day 2. The installation was easy to do in less than an hour and I mean this airbox just looks so. cool.

Advantages: I noticed higher top-end speed and better power throughout the power curve. It also added a real deep sound to the bike which I LOVED. Overall I found myself riding 2-3 seconds a lap faster compared to laps that same day with a standard airbox.

Disadvantages: While the installation was pretty straightforward forward it just sucks that you have to take off bodywork and tank to get to the airbox, though that would be the case for any sort of airbox mod though. Not that bad though honestly
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pete berdos
Aug 28, 2022
another great performance upgrade from TST. words can't described how well this airbox works ! besides being a beautiful work of art, it's workmanship shouldn't have to be hidden, BUT to hide the HP gains no one can see, well we know we all can appreciate that ! so feedback I have to offer for this item is having run against other 400s that were similar to mine and doing a 3rd or 4th gear pull, who ever got the jump usually edged out the other bike or one bike would crawl past the other. " VERY IMPRESSIVE" is what I heard after the same pulls with the same bikes ! the difference on this day was I pulled away like I was on a 600, it was bring a gun to a knife fight ! if you're looking for that extra edge, look no further ! this was added to a bike with full exhaust (spark) stock engine TBs ( had stock air box w/ TST stacks and DNA filter ) and tuned prior to replacing airbix

Advantages: increased power

Disadvantages: can't see how pretty it is under the tank !
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Reviews

Hyperpack Bundle for Yamaha MT-03 2020+
Hyperpack Bundle for Yamaha MT-03 2020+
This looks very clean on the bike. I am not a very hands-on person and I could install it very easily. Customer support was great too!
Kendry Grullon
Nov 18, 2024
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