Going from 350 cc saline to 635 cc silicone is a very large increase, especially at 5'3" and 130 lbs. Even if the implant technically fits your chest, it will likely create a much fuller, heavier, and more obviously augmented look. Silicone may feel softer and more natural than saline, but the size difference matters more than the material. A 635 cc implant can increase risks of stretching, bottoming out, rippling, implant visibility, back/neck discomfort, and future revision surgery. Proportion is personal, but if your goal is natural or balanced, I would be cautious. If your goal is a very full, round, high-volume breast, then 635 cc may match that look, but it should be chosen with full understanding of the long-term tissue effects. The implant base width, profile, skin stretch, nipple position, and pocket support are more important than the cc number alone. If the implant is too wide or too heavy for your tissues, the result can look crowded or drop over time. My advice would be to try external sizers, review photos of patients with similar height and weight, and ask your surgeon why 635 cc is appropriate for your exact breast width and tissue quality. If you have any doubt, consider a more moderate increase rather than jumping almost 300 cc in one surgery.