The front calipers on your car are the same as GTi ones anyway, just not painted red, however they will have the smaller carriers as the discs are a different size. To change correctly you will need a pair of 312mm discs, caliper carriers to suit this size, and ideally some new pads. Iirc the shield is big enough or you can bend it slightly to suit. For the rear you will need everything as above but 288mm discs etc.....
HTH, Lee.