nah, i'm not using the ST205 calipers. Most likely using a custom kit. I want bigger than 296mm, plus I want to avoid using spacers. I've heard of issues with ST205 rotors too, people seem to have more luck with the WRX 99+ jobs..
I'm probably going for 326mm WRX STi rotors and Brembos, but a recent price hike on the Brembos has got me on the lookout for other calipers. Alcon, AP Racing and Brembo are all around the 700-800 mark. Harrop... don't bother there $1000+.
Anyways, I ripped off the calipers tonight and measured with the veniers : 131.12mm, so I'm saying 131mm.