GTA The Ballad of Gay Tony - Frosting On The Cake [100%]

The opening cutscene was edited in using another playthrough.
From GTA Wiki:
For some reason, the introduction cutscene of this mission is counted by the game already as the time taken to complete the mission, adding about 2 minutes to the final score. In order to get 100%, the player must skip the cutscene to the point where Tony instructs the player outside his apartment to drive the Limo with Evan.