Will 200cc make a big difference? I currently have 420cc HP gummies. (Photo)

It will likely only increase your cup by 1/4-1/2 a cup size.  The implant selection should be based on a combination of your desired size, soft tissue dynamics, breast base diameter and skin elasticity.  I recommend an in-office examination as well as a detailed discussion with a surgeon who you are comfortable with.   Finally, make sure your surgeon is a Double-Board Certified Plastic Surgeon certified by the American Board of Plastic Surgery (ABPS), a member of the American Society of Plastic Surgery (ASPS), a member of the American Society of Aesthetic Plastic Surgery (ASAPS), and a fellow of the American College of Surgeons (FACS).Best,Dr. DesaiBeverly Hills Institute for Aesthetic Plastic SurgeryHarvard Educated, Beverly Hills & Miami Beach TrainedDouble Board-Certified, Double Fellowship-Trained Beverly Hills Plastic Surgeon

hello flowerbenz  It’s important to know what size bra you currently wear. Is it a 32,
34, 36 bra, and, of course, the cup size? The strap size is important to
know because that affects the diameter of the cup and subsequently the
diameter of the breast implant that we choose. We also need to know your
height, your weight, and it’s helpful to know your dress size as well.
In addition, it would be very helpful if you include photos of
yourself. A front view, a side view, and a three-quarter view are most
helpful. This will let us see if there are any breast asymmetries, if
the breasts are narrow, if the breasts are wide, what your chest wall
looks.
Breast Implant Sizing (generalization for most patients)
32A to 32C needs about 250-275cc34A to 34C needs about 300-350cc36A to 36C needs about 350-400cc

200 cc increase in implant size will make a difference, but whether or not that will be big enough to meet your goals is unknown. It depends on what you consider a big difference. In the average sized patient, adding 200 cc would increase your size by approximately one cup size.

It's not uncommon for women to go a little bigger when it's time to change implants.  If you increase the cc's by 200 you will get at least one cup size bigger if not more.  However, it's important to discuss the implant profile type with your surgeon as well as the volume.  I recommend seeing a plastic surgeon to discuss the look you're going for.

In general, I tell patients that you would need to go up by about 100 cc to see a noticeable and worthwhile difference.  You will be increasing your implant sizes by 50% which should give you a definite noticeable difference.Good luck on your surgery.Hope that helps.

Dear flowerbenz,200cc increase should make some increase in size. Breast implant type and sizing selection is a complicated process and requires a detailed consultation that includes a discussion of your goals, a detailed examination, and a lengthy discussion. But the decision will always start and end with the patient. When it comes to sizing, we have all of our patients find 3 photos of their desired breast size. We ask for naked breast photos because clothing can obscure the true size (push up bras). Next, we consult with patients and go over the photos and take detailed breast measurements during a physical exam. Next, we using a sizing algorithm to determine a range of implants that will work based on the exam and the measurements.Lastly, during the operation, we use silicone sizers in the operating room to see how the size actually looks in the breast. We sit the patient up in the operating room, while asleep of course, and compare the sizer result with their desired look photos. If it is too small, we start the process over with a slightly larger implant. We don't stop until we get the perfect match.Of all of my breast augmentation patients, every one of them has been happy with their size due to this detailed and meticulous process. You don't want to invest time and money into a result that is either too big or too small.You should discuss your concerns with a board-certified plastic surgeon and make sure that your surgeon understands your goals.Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

Thanks for reaching out. You will definitely notice a significant increase in breast size, I would suggest maybe bringing in a few "wish" photos to your surgeon to make sure  you are on the same page as far and end result goals and expectation. Best of luck! Dr. Kachenmeister

Yes, it is likely that you will see a significant difference with about 200 cc increase in breast implant volume.   The much more important question with be: will the 620 cc breast implants be the correct choice when it comes to  achieving your desired outcome?   
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 "big difference" 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.
 Best wishes. 

Increasing your breast implant size by 200cc would give you about a one and a quarter increase in cup size.