Overfilling Natrelle 68MP 390cc

I am getting my surgery first thing tomorrow morning and I just wanted to clarify something to clear my conscious. I've read that many PS like to overfill the implants by 10% of it's volume size. A Natrelle 68MP 390cc has a fill range of 390-420cc's. So an overfill of 10% does that mean up to 429cc or 459cc? If I went with 459cc, which is 39cc more than the max range, will this significantly make my implants look stiff? I am 5'5", 115lbs, 29" ribcage, and a size 34A hoping to achieve a 34D.