You do have boost control dont you?

No boost control is a solid pipe from compressor to actuator, so the actuator will see full compressor pressure.

The aim of any boost control is to calibrate the amount of pressure pumped to the wastegate actuator, to open it when necessery.
If you have no boost control, then to run 25psi you will need a strong spring, but i dont really see any benifit from that, and as i said you are always more than welcome to ask for a -34 if you require one.

If you havent used it we can easily swap it for you but you simply asked me what i would recomend, and that is a-31, ive never had any reason to use otherwise to make 25psi


Heres One good example of a bad point about running a really strong spring,
If you are running say a 14psi spring when pre loaded, or even higher if you have no boost control, when it comes to mapping how are you going to reach the low boost areas under that? The minimum boost your actuator will run is 14psi so how are you going to map 6k rpm at 10psi? you end up with lots of area of the map you will really struggle to reach and this can be dangerous for various reasons, What if one day you develop an air leak and do manage to reach these low boost areas that have not been correctly mapped?
The softer the spring you can get away with using the more boost control you will ultimatley have.

Also for those running aftermarket electctronic boost control its nice to be able to turn the boost right down, with a strong actuator spring you can never run a boost pressure lower than the actuator spring pressure, so in this instance its nice to run a softer spring you then have so much more controlability of your boost pressure.