"I'd like to purchase a used eBike. The previous owner said that he made a "few improvements to the eBike components". What does Bosch think of this?"
Our advice: Always decline offers of this kind. The Bosch eBike system is designed for maximum safety and durability, all system components are controlled and monitored by extremely complex software. Any intervention in the system design will almost certainly have a negative effect on performance. Possible consequence: The safety of the rider is endangered and use of the system may contravene statutory regulations.