Titleist 917 Metalwoods Article

[boogielicious]

http://www.golfdigest.com/story/new-titleist-917-metalwoods-add-adjustable-sole-weight

Adjustable weights for CG adjustment.

Quote

The 917 drivers, the 917D2 and 917D3, feature several upgrades from the 915 drivers. Most notable are refinements to the channel at the front part of the sole to improve flexibility in the lower half of the face and also reduce spin. The channel has been selectively thinned in the heel and toe section compared to the 915’s constant thickness.

Also enhanced is the 917 drivers’ face insert. The variable thickness face features eight distinct areas around the center section. Each section is designed with a constant thickness that varies from section to section and is consistently thinner in the top and bottom of the face than they were on the 915 drivers.

 

[Missouri Swede]

I saw a review of the drivers on another website.  By their testing (sample size of 1 golfer), it showed 917 models with a little increase in club head speed, but slightly decreased ball speed, and lower launch angles, shorter carry and shorter distance, compared with the 915 models. 

But I guess they sound better.