As far as i can work out it uses pressure from the inlet to hold the wastegate closed for longer supposedly getting the turbo to spool up a bit quicker according to the write up in fast ford a few years ago............

Will let u know tony, is a -31 or -34 better on a t34 with .63 housing?! would also need an amal valve if im gonna go back to a normal actuator. Althou would have to cut the controller for it out as julian godfreys fitted it and they have glued it to that blanking plate thing on the dash and glued the plate in too