cheap option would be to fit GTI 8v 239 vented discs & pads up front, these will fit straight on though you may need to replace the caliper slider bolts with GTI items. If you want to go larger, you can fit 256 or 280mm brakes. To do this you'll need to replace the wheel hubs with 16v 256mm ones or G60 280mm ones, then fit the matching calipers & carriers.