not 100% but i think the 16v had 256mm and the 8v had 239... not sure about the rear discs..
upgrade wise, straight swap for the 280mm g60's, and these can be found on loads of dubs, audis and seats... just bolt off the hub and bolt on the new one and away you go... easiest brake upgrade around, plus its a standard part for easy to get replacement discs and pads from local factors...
rob