GC Boost UP is an installable performance-enhancing component for Extreme Gears. Its actual appearance is unknown, though it is presented as an icon on the head-up display in the top-left corner of the game screen. Its icon is a light blue-colored circle with a black Extreme Gear surrounded by a flaming aura inscribed in it.
In the game, GC Boost UP is permanently installed into only certain Extreme Gears. When in use, GC Boost UP increases the velocity of the speed boost that comes at the end of performing Gravity Control, allowing the player to reach higher speeds than normal after performing a sharp turn with Gravity Control.
As an unmentioned additional effect, GC Boost UP also increases the number of Gravity Points the player accumulates from getting certain TrickRanks or when accessing Wall Routes with Gravity Control. The amount of additional Gravity Points earned from performing the aforementioned actions and the range of actions to earn them from increases by the number of GC Boost UPs used at the same time. However, the additional Gravity Points gained from using more GC Boost UPs differs between each Extreme Gear. In Normal Race, the bonus Gravity Points earned via GC Boost UP is not affected by the GP accumulation modifier setting. The amount of additional Gravity Points earned from their respective actions for each Extreme Gear are listed in the tables below:
In gameplay, GC Boost UP and its ability will be disabled when starting a new race. To activate GC Boost UP, the player must press one of the following buttons after collecting a certain number of Rings:
Wii (remote) - sideways
Wii (remote) - forward
Wii (Nintendo GameCube Controller)
When activating GC Boost UP, the player's Rings will be reduced accordingly by the number needed to enable it and the Extreme Gear is surrounded by an orange void, indicating the Gear Part's ability is in effect. At this point, whenever the player performs Gravity Control, their Ark of the Cosmos/Gravity Band glows in a color which depends on how many GC Boost UP Gear Parts have been activated. The following Extreme Gears come equipped with the GC Boost UP: