Q: Is this safe to add/remove to an existing save?
A: Yes! This doesn't modify any save-related data.

Q: Does this work in multiplayer?
A: Yes, but the server may need DoLuaChecksum disabled.

Q: Compatible with car mods?
A: Yes, as long as the car mod doesn't have a custom dashboard. Though you will either need to select "ALL' or create a custom ubiquity list for any of those modded vehicles to have a TPMS.