Just wondering the answer to this question... since im sure evo's can get this problem the subaru boards werent very helpful ....and im trying to find the answer to this so i know what to buy...

put the car on the dyno yesterday... my stock turbo sti, setup on a tial 44mm EWG was leaking out a bit of boost the second they hit the throttle...

its a 7lb spring inside... Do you think the car is actually forcing the wastegate to slightly open because the EWG spring is too small? My tuner said that its causing the car to spool 700ish rpms late.

Just trying to diagnose the problem...

 

Yes too small a spring can cause the wastegate to open.

From my memory, the behaviour you generally see when this happens is the boost hits to a point, and then creeps up from there. Rather that just hitting your boost set point right away.

For my car, with a 35R kit, when I first got it I only had a 10 psi spring. I could not really run more than 20 psi with that without the boost not doing what we wanted. I run 22 psi of springs now, and can run as much as 35 psi very easy.

Keep in mind, the spring pressure yuo put in the wastegate will be your minimum boost level.

 

just an update to those that may have the problem in the future...

the wastegate had a small blue spring which is 7.2psi
i switched to the 1 bar, 13.5 psi and boom! problem solved...

...now to find that pesky exhaust leak... im putting an EL header on the car and taking off this stock manifold. The EL header will make my car sound like an evo