The Hoverboard Turbocharger is an upgrade that greatly increases the player's Hoverboard speed. This Upgrader is obtainable from Ghost Hunter Yoko's last quest. It can be disabled in the Settings under Hoverboard Turbocharger (ON/OFF) or manually disabling the boost on top of the ectoplasm bar.
It is also used in a Race Event automatically, if you have it or not.