The distance between breast implants, which will determine how much cleavage you have after a breast augmentation, is determined by your anatomy. If your breasts are far apart before surgery, you will most likely have a wider space between them after surgery. If your breasts are close together before surgery, the implants will be closer together after surgery. Whether the implants are under the muscle will also affect this since the muscle attaches to the breastbone. If the muscle happens to attach at the outer edge of a wide breastbone the implants will be farther apart.