Hell, I think I might do this eventually once my wideband comes in and I get a laptop for my fuel controller. Just remember this though, the tension in the spring (2lbs for example) does not necessarily translate to +2psi. Since psi is lbs/sq in. You have to take into account the area of the wastegate actuator diaphragm(whatever that may be). If it is less than 1sq in then one extra pound of force will require >1psi to open, and if it is bigger than 1sq. in. then it will be less than 1psi extra boost per pound of tension.