there was a TV prog on channel4 last week showing the gals with the biggest silicon funbags .enormous great things ,which when removed after some years had bags with nasty black deposits floating around .so they appear to have a shelf life despite all the lifetime guarantees .
One gal in Brazil was shown on the op table with her aureolas removed and new saline liquid being pumped into the existing bags to boost the size to the biggest in the world .
'maxi mounds' the gal with biggest was unavailable for filming .
http://en.wikipedia.org/wiki/Maxi_Mounds