From ETKA, the mk5 GTI has a 282 mm rear disc and the mk6 GTI has a 272 mm rear disc.
The caliper has different codes but I think that they are the same.
Not exactly, mate.
Mk.V GTI + Mk.VI GTI up to 2010
> 286 x 12 mm rotors with
TRW calipers
Mk.VI GTI from 2010 on + most Sciroccos
> 272 x 10 mm rotors with
Bosch calipers
They look different and are quite easy to recognize. TRW calipers have a
curved yoke, Bosch
calipers have a
straight one.
If you still have the first pads: Most TRW calipers came with TRW/Ferodo pads. All the Bosch
calipers I've seen came with Bosch pads which are labeled "Bosch" on the backing plate.