Oldrich Widman of Dream Entertainment, Prague - Silvia's original manager, and also the manager of Daniella Rush, the late Lea De Mae and young Monica Sweetheart ("The Dream Team") always criticised the USA stars for enhancing their breasts.
Silvia's assets seem to be the same as when she started work in the glamour movie business in about October 1996 and as far as I know, they are still natural.
It would be strange if Silvia had gone against her manager's strong feelings.
You may remember one of Silvia's earliest films (directed by Frank Thring) was a "Lee Nover" movie episode in "The Search for the Perfect Breasts" (or a similar title). It should be included in the film titles big Movie List that I once made. I doubt if enhanced breasts would have been considered acceptable for that title.