Although I don't know much about silicone, saline under the muscle probably looks the same as silicone because the pectoral muscle covers most of the implant. Overs look very round and eye-appealing, but are not necessarily an option to everyone. It really depends on what kind of breasts, size, elasticity, etc she has right now. Under provides more of a lifting appearrance for someone who might need a lift in the somewhat near future. The overs, in some cases, tend to sag more with time, but have a much shorter recovery time. I wanted overs, but my surgeon told me that unders would look best for my breast type.