I have an sti 4, and every now and then, when I re-apply the throttle, it sounds like the exhaust goes quiet and I have very little boost for a a couple of seconds. If I lift and re-apply the throttle again, I get the boost + exhaust noise back.
I did notice once before when I was checking the engine over, that the actuator arm was seized and I have to get some pipe-grips out to free it off.

Could it just need cleaning??

Any info appreciated.

Chris