From
http://uk-mkivs.net/forums/p/153276/1014271.aspx#1014271
Heres all the brake sizes on the VAG range, and what they are fitted to as standard.
VW Golf R32 | Audi TT 3.2 Quattro
The Front brakes are 334mm x 32mm Vented 2-piece Discs, Twin piston(32mm/42mm) calipers
The Rear brakes are 256mm x 22mm Vented Discs, 38mm Lucas singles
Seat Leon Cupra R
The Front brakes are 323mm x 28mm Vented (grooved/drilled option) discs with 4 piston(34/38mm) Brembo calipers
The rear brakes are 256mm x 22mm Vented , with 38m Lucas single piston calipers
Audi TT-Quattro (225hp) | VW Golf anniversary | Golf GTI AUQ | Skodá Octavia VRS | VW Golf V5 170 | VW Golf V6 4 Motion
The Front brakes are 312mm x 25mm Vented Discs, 54mm ATE single piston calipers
The Rear brakes are 256mm x 22mm Vented Discs, 38mm Lucas single Piston calipers
Audi TT (180hp)
The Front brakes are 312mm x 25mm Vented Discs, 54mm ATE single piston calipers
The Rear brakes are 232mm x 9mm Solid Discs,
Golf GTI 1.8T | Golf 130/150 TDI | Golf V5 150 | Seat Leon 130/150 TDI and 20VT
The Front brakes are 288mm x 25mm Vented Discs, 54mm ATE single piston calipers
The Rear brakes are 232mm x 9mm Solid Discs
Golf 2.0 8v | 1.8 | TDI 115 | TDI 110 | TDI 100 | TDI 90
The Front brakes are 280mm x 22mm Vented Discs, Single piston calipers, caliper carrier integrated into hub (FS III's)
The Rear brakes are 232mm x 9mm Solid discs
Golf 1.4 16V | Golf 1.6 16v | Golf 1.6 8v | SDI
The Front brakes are 256mm x 22mm Vented Discs, single piston calipers, carriers integrated into hub (FS III's)
The Rear brakes are 232mm x 9mm Solid Discs