We see Excelsior again Star Trek VI: The Undiscovered World and its maximum speed on the warp speed scale has never been named. However, a cut line of dialogue from the movie suggests that its top speed is 9. From a fan perspective, this could be part of how Starfleet has rebalanced the scale between live-action shows.
No official Star Trek movie or show has ever officially commented on the warp scale change or what happened to Starfleet’s transwarp drive test. Regarding the latter, the closest thing we got to an explanation was a line in the first edition of Star Trek Chronology saying that Starfleet considered the test a failure and fitted the Excelsior with a normal drive. According to this fan theory, it is a combination of Excelsior’s previous research and cutting line from it The Undiscovered World may ultimately explain the warp scale change.
Source link
