Which of the following enhancements does NOT improve surface-level integration?

The correct choice is related to the nature of surface-level integration, which involves the ways in which different systems communicate and work together at an interface level. Enhancements that improve surface-level integration focus on ensuring interoperability, understanding dependencies, and ensuring that outputs align with expectations.

Creating exhaustive user stories is primarily a technique used in agile methodologies to capture requirements from the user's perspective. While user stories are instrumental in defining what needs to be delivered and identifying functionalities needed by end-users, they do not directly address how systems integrate or interact at a surface level. Instead, they are more about capturing business needs and ensuring the development team understands what to build, rather than enhancing the technical components of system integration.

In contrast, identifying impacts to other systems focuses on understanding how changes in one part of the ecosystem will affect others, which is critical for successful integration. Documenting feature requirements ensures that all necessary functionalities are defined, aiding in precise integration. Testing system outputs ensures that the systems produce the expected results when integrated, which is crucial to verifying integration's success.

Therefore, while all other options contribute directly to the integration process, creating exhaustive user stories does not inherently improve surface-level integration, as it deals more with requirement gathering than with integration mechanics.