stock turbo + MBC = boost taper theory

[CarPsyco84]

Internal gates are pretty well known to get blown open at higher rpms because the exhaust pressure pre-turbo is higher from the higher airflow through the engine. I used a hardware store spring on my wastegate back in the day, and It ran around 17psi with no boost controller and it seemed to hold the boost more stable than without it. Without the helper spring it would spike 2-3psi higher and then fall back.