Second boob job - how can I achieve more volume but not look too large? (Photos)

Hi, I had my silicone implants placed under the muscle 11 years ago. I'm getting them replaced in a few weeks time. I said I'd like if possible, just some more volume in the upper area but not for them to look ridiculously large. The surgeon surgeon for me to pick between 500cc and 550cc. Could you advise which size / would either option would likely look good on my frame still? Would I notice a difference with 500cc? Thanks Georgia