Goals must be acceptable . Not so difficult that they are seen as unrealistic or that they are rejected. Get them to buy into the goals. However, there is no evidence that participation by itself leads to greater levels of performance. Participation can increase the likelihood that goals will be communicated and understood.
Participation has a greater effect on worker satisfaction than on performance.
It would appear, further, that through participation you can increase satisfaction at no cost to performance. Participation can also result in better understanding of goals. By participating one learns more about problems, constraints, objectives, etc. But not always. I have been to many meetings where people came out with different interpretations of the goals.