It shortens the face because the mandibular angle decreases. Typically in cases like these a sliding genioplasty is needed too, to bring the chin forward and up a bit to be normal but sometimes small enough of a discrepancy it's not worth the extra morbidity. My plan is almost identical except my starting airway is 3x larger and I don't need the 3mm impaction. The latter property reduces my mandibular movement by 8-10mm, pretty crazy. Going to need a graft for a large movement like this. I wonder what the surgeon will do about that piece sticking out, shave it down I guess? The good news is that the lip thins with the advancement so that 7mm movement "should" have a net effect of only 3-4mm and the ANS is typically shaved to reduce tipping the nose however flaring of the nostrials is inevitable.