They are fairly recent additions, probably for the benefit of the Physique judges, but maybe for her own self confidence. It's her body, afterall.
The reason they look fairly realistic is as lovebiceps says, she has been sensible re the size, but also she keeps them covered so the artificial shape where her body ends and the implants start,and stretch marks, are not visible. FBB's do look OK with Implants, when clothes are kept on. And we have to remember that FBB's have a life off stage as well.
The problem comes when competing, on a dieted frame, they don't look good at all, and the cartoon comments start.
Klaudia has got it right, although it is not something I would have said she needed to do, I think she looked just as good before the op.