Here are a couple of helpful points based on my three decades of experience.
If your surgeon concluded that 415 cc was the largest size your chest skin and breast tissue would accept at the time of your surgery without being excessively round or tight you do have the option (if you wish to) of replacing the implants with larger implants 12-18+ months after the initial surgery. The reason is that the weight and volume of your implants stretch and relax your skin in time permitting a change to a larger implant. I feel that the best method of choosing an implant is to show pictures of your goal to your plastic surgeon and allow him/her to choose the final implant size during the procedure when your actual size and contour can be seen with test or sizer implants.
I'd also point out that the risk of complications or future complications/disappointment increases with implants that are disproportionate to your skin surface area and tissue thickness/elasticity. Problems such as rippling, visible waviness and implant displacement or descent can become troublesome with very large implants so consider being a little more rather than less conservative with your change. Good luck and best wishes,
Jon A Perlman MD FACS
Certified, American Board of Plastic Surgery
Extreme Makeover Surgeon ABC TV
Best of Los Angeles Award 2015, 2016
Beverly Hills, Ca