Can 350cc Breast Implants Be Filled to 375cc?

The implant manufactures have a recommended range for filling of saline implants. Assuming your implants are not inflated to maximum recommended volume, it should be a safe and relatively easy procedure to add 25cc of saline. I, however, would not recommend this procedure. A 25cc increase in volume is small and would not provide substantial added augmentation. It therefore is hard to justify the costs and potential risks for even this relatively minor procedure.
I hope you are not dismayed by this answer. Best wishes to you.

I assume you are referring to saline implants. Saline implants are produced with a recommended fill volume range. The ranges vary for different styles as well as manufacturers.
For example, some implants state: 350 + 50  -00. This means it can be filled from 350 to 400cc

In contrast to gel implants, saline implants will have a recommended "fill volume." The surgeon therefore has a range of fluid that can be placed into the implant. You should receive an implant card after your procedure which has the size of the implant and how much fluid was placed into the implant by your surgeon. Filling the implant to the maximum recommended volume will decrease rippling in the implant and is commonly practiced. However, "overfilling" the implant beyond the recommended range can void your implant warranty so be sure and check with your surgeon before the implants are placed. Generally, a "350cc" implant can be filled to "375cc's."