Implant exchange. 375cc to 550/600 cc. Good idea?

Going from a high profile implant which likely fits your base diameter well to a larger implant would likely require a bit of capsule work to open things up a bit.  You may be able to go larger, an exam would be appropriate to see how much larger you can go, but to go to a moderate plus implant of 550-600 cc would be tremendously wider than your breast width.  You would probably want to be looking at high profile or ultra high profile if you are looking at that large of a cc.Again, it is possible but an exam would be necessary to see what would be ideal.  Going beyond your measurements will just lead to problems, in particular rippling, in the future.Hope that helps.

Thank you for the question. You will find that online consultants will not be able to provide you with specific advice in regards to selection of specific breast implant size/profile.  Adjustment of the breast implant capsules may also be necessary.
Ultimately, careful communication of your goals (in my practice I prefer the use of goal pictures, direct examination/communication in front of a full-length mirror, and computer imaging) will be critical. 
Generally speaking, the best online advice I can give to ladies who are considering revisionary breast augmentation surgery (regarding breast implant size/profile selection) is:
1. Concentrate on choosing your plastic surgeon carefully. Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you are looking for. Ask to see lots of examples of his/her work.
2. Have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining breast implant size/type/profile will most likely help achieve your goals. 
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or "D or DD cup” or "bigger/fuller look" etc means different things to different people and therefore prove unhelpful.
Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup size may also be inaccurate. 
3. Once you feel you have communicated your goals clearly, allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals. Again, in my practice, this decision is usually made during surgery ( after the use of temporary intraoperative sizers). Viewing the patient's chest wall in the upright and supine positions, with temporary sizes in place, help select the best breast implant size/profile for the specific patient.
I hope this helps. Best wishes.