Ive had 16vT pads fit into the 97/99
GT3 ATE calipers. if you do it renew the Gts 257mm discs at the same time otherwise you dont get the benefit of the larger pad friction area.on old discs youll just grate the inside edge of the pad to nothing.
oh and the 16vTs 284mm discs wont fit so this is a low cost upgrade that lets you run bigger pads in your existing calipers and I would say you have a better choice of pad material if you look up 16vT pad specs.