I don't see GS getting tight or nervous being at home. That doesn't make sense. Who gets nervous when they are in familiar surroundings?? There is no pressure on this GS team. They are playing with house money. They are not supposed to win this series and they know it. When you have nothing to lose, you can be carefree and loose.
That being said, the Spurs need to run GS off of the 3-point line. Give GS two point shots. Basically this series is the Spurs frontcourt vs. the Warriors backcourt. You can't win that matchup giving up 45% shooting from 3. Force them to take two point shots and you can win this series.