The primary effect of Graviton Generators is to increase the radius of Gravity Well, not the pull.
GW Rank 1 radius is 2.7km base, or 3.4km with 99 Graviton
GW Rank 2 radius is 2.85km base, or 3.56km with 99 Graviton
GW Rank 3 radius is 3.0km base, or 3.75km with 99 Graviton
When I concurred that it affected the pull, I should have clarified that I meant that they extend the range of Gravity Well (thereby, extending the range of the pull), not that it makes the pull stronger. I edited my previous mark to make that clarification.