The damper in the 2020-2023 Boxxer C2 can be upgraded/replaced with the Charger 2.1 RC2, which is part number 00.4020.171.000 (DAMPER UPGRADE KIT - CHARGER2.1 RC2 CROWN HIGH SPEED, LOW SPEED COMPRESSION (INCLUDES COMPLETE RIGHT SIDE INTERNALS) - BOXXER 27.5"/29" C1-C2 (2019-2023)).
RockShox service kits and spare parts are best obtained through your local shop or dealer. See our dealer locator, below, to find a dealer near you. If no one is currently listed near you, then please search for local shops via your preferred web browser.
https://www.sram.com/en/dealer-locator
Manuals and additional information about RockShox and SRAM components can be found at our service site, linked below.
https://www.sram.com/en/service
Further questions?
Reach out to Rider Support by Asking A Question at the link below.
https://www.sram.com/en/rockshox/campaigns/rockshox-rider-support