Swapped all the components on the diesel to 288mm front and standard rear disc setup from a vr6. Only problem that you will face is the rear bias valve if your diesel doesn't have abs. You can leave the rear beam on the car and swap over all of the hubs and calipers etc but may need brake lines made up from the bias valve. Mine was completely corroded and not working anyway so i just scrapped it and left the tdi master cylinder on. I will warn you that it does lock the rears if i massively stand on the brakes in the wet, but for day to day driving its fine. The swap itself isnt that hard as the whole front hub/lower arm/driveshaft from the gti fits straight on, 2 bolts on the lower arm, 2 bolts on the hub and 6 spline bolts on the driveshaft, then obviously the brake lines.
