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I recently changed my stock turbo with a used GT35. Reason being my mechanic said the wast gate actuator diaphragm was leaking and so it would over boost. Now that I have the GT35 in with a brand new Tial 38mm external waste gate, I'm still overboosting. I suspect its the E-Street Boost electronic controller but he says it because the waste gate is to small. Any advice in correct diagnosing the problem and rectifing the issue would me much appreciated.