If you get it wrong and are to slow to open the vanes whilst the turbo is accelerating you may risk over boosting your engine.
I think there will be more to setting this up than meets the eye, it sounds like a fairly straight forward mod, but get it wrong and you maybe in trouble.
Setting it up on a test bed with the turbo spinning is the only real way, open the vanes up to fast and you will bog the turbine down, to slow and you may over boost, having the diaphram react to boost pressure is one thing but you also need the correct spring on the other side to allow it to react at the right rate.

