1gen VR4 GTO. 4bolt block with forged crank. 15G hong kong hairdryers and supporting mods.
I tested his wastegates (that came with the turbos) with hand. They felt really loose even compared to stock ones.Something is up with that you should be able to blow past 15psi with stock wastegates.
And with his T25 flange turbos the wastegate flap is bigger in diameter, and the flap arm is also longer. So I believe that with the same backpressure the bigger area of the flap valve generates more force, witch is multiplied with the longer arm of force, combined with weak wastegates would explain why backpressure is able to open the WG:s with lower boost that with stock turbos.
But yeah im just guessing.