The Kaaz is the only aftermarket clutch LSD that I know of for the focus. The torsen style work well, but when one wheel is completely off the ground the diff will still be open. The clutch style will still transfer torque to the outside wheel.
Parking Lot Hero
2008 WRX daily driver
2003 ZX3 23D Autox Car 42 FSP
"Hella Functional - Raced, Not Hard Parked"