on my saff the actuator is stamped 14 psi where is this from and whot is the bennifets of this actuator apposed to a -31 or is the -31 a better actuator to have?

 

14psi will just be the pre-set spring rating on the actuator. ie the wastegate will open at 14psi with out pre- loading the actuator
IIRC -31 actuator pre-load is set to about 10psi although you can load em up a fair bit more..
An actuator is an actuator at the end of the day.. all it is is a spring that pushes a bar when the preassure gets too high..
The difference is prob gonna be in how long they last and how good they are actually made..
i would allways buy a 'propper' one ie garret etc instead of a fancy alloy one that prob has a shite spring in it

 

the one i have got(14psi) looks like a garret actuator but its silver in sted of gold