The 280mm brakes are 22mm thick, the 256's are 20mm. On the Lucas 54 caliper, the pads are too thick for the gap that's left, so you either turn down the disc or machine the pad. Get it wrong and the pad drags and warps the discs, which is why mine vibrates under braking. They will work with Polo 6N2 GTi calipers as the GTi uses a 256x25 disc and the caliper is wider. The pads are the same. Going back to standard will give me 3 cars with the same brakes, 14" rims, and I've never felt like I need any extra. I don't even need to bleed anything if I just swap carriers.