Ninja400R Velocity Stacks – Kawasaki Ninja 400 / Z400


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After countless hours of dyno testing, our Superbike Velocity Stacks are ready.

*We strongly recommend using our ECU flash tuned specifically for our velocity stacks or an aRacer RC2 ECU paired with the new velocity stacks.  We have re-tuned each cylinder to match the new velocity stack lengths.

*If you have already purchased our ECU Flash for your bike and now you want to install our Superbike Velocity stacks, please contact us to update your ECU mapping to match the Velocity stacks.

*Velocity stacks will now include a template for cutting the large opening in your airbox that will fit our Ram Air System incase you choose to upgrade down the road.


Ninja400R Superbike Velocity Stacks – Kawasaki Ninja 400 / Z400

The OEM Airbox in the Ninja 400 / Z400 contains two different length velocity stacks, a long one and a short one.  This kit replaces both stacks with our own spec shorter velocity stacks designed by Jeremy Toye.  The performance difference with the Superbike Velocity Stacks compared to the stock is dramatic.  The power curve with the stock setup falls off pretty fast after 9500, but with our velocity stack setup, it continues to climb all the way to 11,800, maximizing power for high RPM track use.  For maximum performance, it is recommended to use our Superbike ECU flash or aRacer RC2 ECU with the new velocity stack setup to correctly tune each cylinder to the new Velocity stack lengths.  Here’s a dyno comparison with a stock motor and stock airbox vs modified airbox (snorkels removed) with Ninja400R velocity stacks.  You can see the power band carries strong almost all the way to red line instead of falling off at 9500 and we don’t lose any important midrange power.

Norton Flash Ninja400R Velocity Stacks Spark Exhaust Dyno Chart Norton Motorsports

We recommend the following airbox modifications be done to maximize performance of our Superbike Velocity Stacks:

Norton Motorsports Superbike Velocity Stacks Modify OEM Airbox Kawasaki Ninja 400


Additional information

Weight 0.1 lbs
Dimensions 6 × 4 × 3 in



  1. Michael (verified owner)

    I ordered these velocity stacks as part of Norton’s ECU flash, exhaust and velocity stack package deal. The stacks are easy to install, and i can feel a huge change in power when riding. I am very happy with my purchase, these velocity stacks work!! My bike pulls strong all the way to the rev limiter!!! I didn’t feel a loss of power at lower RPM’s, and the power really starts coming on strong a little less than halfway through the RPM range.
    When you buy from Norton Motorsports, you can be assured you are buying a top quality product from a company that stands behind their products and sales. Emails are always answered quickly, with accurate information.

  2. Dallas

    Thank You, Jesse!!!!!
    What a night and day difference after installing the Norton velocity stacks with the ecu flash (19′ Z400). Really wakes this bike up, throttle response is way smoother and the bike pulls harder all the way through the rev range. Best of all is no more lean condition and the bike runs much cooler, all around best bang for your buck upgrade you can do for the ex400 platform. Installation is easy if you are mechanically inclined, took me about an hour including flashing the ecu myself.
    Norton’s customer service is second to none, even with some unexpected delays with my order Norton Motorsports was transparent and helpful throughout my experience.

  3. Jason Borowski (verified owner)

    Big difference, when paired with the ecu tune and a full exhaust. This should be a mod for anyone who wants to keep their ninja 400 for a long time.

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