From GOLF Magazine:
Callaway's stealth-like FT-iQ driver is engineered to swing fast and hit hard. "It's our most energy-efficient face with our most stable head," says Dr. Alan Hocknell, Callaway's VP of Innovation and Advanced Design. In short, it boosts ball speedfor longer drivesdue to a hyperbolic face design, high MOI and precise center of gravity (CG) location. The turbocharged titanium face (with an "X" pattern behind the hitting area) is thickest in the center and becomes rapidly thinner in the perimeter. This construction delivers consistent ball speed across the face so misses carry nearly as far as center strikes.
A tapered, lightweight composite body gets the club's center of gravity twice as low (and more rearward) than FT-i, resulting in 300 rpm less backspin. That's significant because FT-i was known to produce too much spin, particularly at higher swing speeds. In addition, the rear chamber (including weights) accounts for 18 percent of the head's total mass. The payoff is greater controlMOI is 8 percent higher than FT-i; shot curvature is 35 percent less than FT-ioff the tee.