Ford America did a V8 focus using a modular V8, they called it the Focus RS8. (based on the European Mk1 RS)
Type: V8 5.0 Litre
Power kW at RPM: 309 / 6700
Torque Nm at RPM: 502 / 5000
Rear-Wheel Drive.
You can buy the kit through Ford Performance parts or SVT in the US.