Does the X3 program work on my core and abs?

While there are no ab specific exercises, research indicates that the deadlift and the front squat exercises activate the abdominal muscles more effectively than ab-specific exercises. Abs are stabilizing muscles, which grow when used as such.

The X3 bar 12 week program stimulates these even more because the weight goes up, as you move into stronger ranges. With X3 there is more activation, more natural growth hormone triggering (this is a growth hormone axis) and more ab growth.