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