I have a 2011 Subaru WRX. I think the wastegate is not opening. Is the wastegate suppose to open while car in neutral and pushing on the gas, or just while driving in gear? Thanks.
While the engine is not under heavy load, it is highly unlikely that the turbo will spin up enough to cause sufficient pressure to require the waste-gate to open, so in neutral it will definitely not open.
It is highly likely that you would need to be doing a decent amount of acceleration before the waste-gate opens.
While monitoring the boost pressure in my car while driving, it was only while accelerating up a hill that I managed to reach maximum boost easily. The waste-gate would only need to open as maximum boost approached.
The function of the wastegate is to dump or bleed-off excess pressure when the engine is getting boost from the turbo. Just revving in neutral will not provide maximum boost.
Note, some cars have vv turbos (variable vane) and don't have that issue as the ecu controls the max pressure delivered by the turbo to match the "best" output for the engine - much more efficient...
Most turbos can provide more boost than the engine should receive, so the wastegate stops the engine from getting damaged. A quick search on youtube will show you what can happen if you overboost an engine.
A friend had the pipe to the wastegate fail and the engine got extra boost... He liked the good acceleration, but as it was an old car, he was not worried about reducing the engine life...