How much better can titanium be? Titleist went to Mars to find out. These drivers use a titanium alloy (ATI 425) in the face originally developed for NASA’s Phoenix Mars Lander. In other words, it’s light, flexible, strong and resilient—just the right material to smash a golf ball. This alloy’s strength-to-weight ratio allowed the designers to pursue a more aggressive variable-thickness face to get more distance. Ball speed is great, of course, but using a lighter material improves the forgiveness in these heads, too: The deeper and lower center of gravity offers increased stability on strikes toward the heel and toe and low and high. The result is consistent spin and launch conditions for a more efficient ball flight—even on less-efficient impacts. Titleist made aerodynamic shaping a priority for both heads, but each features a different look and focus. The TSi2’s larger shape speaks to its overall forgiveness and higher launch. The more compact, flatter-launching TSi3 uses its extra mass in an eight-gram rear perimeter weight chip that fits into five settings. Read more >>