910 D2 Weight Change

My current 910 D2 driver has a 7 g. Weight.  What does increasing/decreasing this weight achieve with all other things the same?

Changing the weight would increase or decrease the swingweight, or club head feel, of the club, all things else left the same. Adding weight would give you the impression of more club head weight, and decreasing it would take away the feel of the club head weight during your swing.