Have fitted FOCUS RS BREMBO,S to mine.As FOGARTY said ,the only problem is fitting wheels over them.The only wheel i know of that fits are COMPOMOTIVES.You will need :

1.FOCUS RS DISCS &PADS
2.FOCUS RS CALIPERS
3.LONGER FLEXY HOSES
4.ADAPTER BRACKETS (ZOO MOTORSAPORT) £60

Here,s some pics of them fitted on mine.The calipers come silver so i painted mine red.









As you can see from these 2 pics my old 17,s fiited on but as soon as you spin the wheel it catches on the spokes.







COMPOMOTIVES ONLY i,m affraid.