Hello, before doing any upgrades to the front brakes you will need to fit St170 hubs as the calliper is integrated to the hub on a standard focus but the st170 are bolt on. The rear brakes are likely to be drums, these can be removed and hubs fitted for disk brakes just 4 bolts each side but you will need custom flexible hoses as the drum brake lines go up the wheel arch where the disk brake lines go along the arms.