As several colleagues have replied, it is not particularly helpful for patients to worry about implant size and it is a bit like speaking with your contractor regarding what size pipes or joists he plans to use when building your house. As a patient, it is most important for you to share with your plastic surgeon your aesthetic goals--what you hope to look like. Your plastic surgeon has the expertise to determine how to best accomplish that for you and will not only factor in what type of implant to use and the optimal size (width, height, projection) but also which surgical technique to use. You can and should participate in the conversation and make an informed decision regarding incision placement, smooth versus textured, round versus shaped, under versus over the muscle, etc. but ultimately you want to rely on your plastic surgeon to make the specific decision about implant dimensions. If you remain unconvinced about his or her recommendations, I suggest a second or even third opinion until you feel that your aesthetics align with those of your surgeon. Best of luck to you.
The difference between the two implants you have mentioned is 40cc. That's about 3 table spoons. In my experience, it would make little if any difference.
