The actuator is essentially a pressure switch
The actuator is the cylindrical unit attached to the compressor housing with an actuator rod going to the turbine housing.
The actuator has a pre-set spring inside it that compresses under a certain PSI. The actuator is connected to the intake via vacuum hose, and this is where it gets its pressure reading from. When the pressure from the intake reaches the springs compression load, the actuator rod moves a flap on the inside of the exhaust housing which diverts gases straight to the exhaust instead of through the turbine. If too little pressure is made, then the flap closes. Its all goverened by pressure.
The reason I say 'sell it if its a T25G' is because the T25G is too big and laggy for such a small capacity engine. The turbo takes long to spool and makes the same power in the end as a T25.
A perfect turbo for the CG13DE would have to be the GT25, which is in essence a ball bearing variant of the T25, albeit with different trim angles on the compressor side though.
Sean