It is possible to get implants that look and sit natural, especially if you have a bit of boob to begin with. A friend of mine went from a C to a D cup and they look completely real. She had a bit of sag in her natural boobs which helped the implants sit more natural.
I was leaning towards them being real, but when I saw footage of her on her back whilst sunbaking, her boobs don't fall to the sides like natural boobs do, so that leads me to believe they are fake (anatomical/teardrop style).
If they are indeed real, she is very very lucky. Her body proportions are perfect.
I think Krystal Ince BB04 had the best boobs of any BB contestant.