External wastegates Vs std actuators

[CNHSS1]

Currently im running a T28 Turbo Technics hybrid with a normal style actuator. its got an adjustable arm which has the arm wound on loadsa turns of preload to give 12psi static opening with another 4psi achieved (16psi total) with a boost solenoid controlled by my ecu.
Is so much preload on the actuator arm accurate enough?
should i:-
A) buy a trick adjustable actuator that is adjustable internally? if so what makes etc
B) go for an external wastegate and lock the internal wastegate flap solid. Fitting one wont be an issue as i have a tubular maifold to go on, but what makes etc. I have seen some on ebay but they generally say 3.8psi or 5.8psi springs or just say adjustable. Has someone got the instructions for one i can have a look at or more info. Ive contacted the sellers on ebay for a few now and no f*cker has even replied!

im looking to run 12psi-14psi min 'static' with up to 20psi via a boost solenoid

actuator is the easiest method as far as i can see, less to go wrong and less weight which is important on my little plastic car
Your thoughts please gentlemen.......