Did a bunch of test drives to configure the new single wastegate, and the MAP problem is still there! Boooo; yup, boost drops off exactly the same as before at the same 7500 rpm. The thing is, with the 4-port boost control valve, the ECU’s closed loop boost controller should adjust the duty cycle to compensate, as the 4-port controller allows it to gate MAP pressure to assist the spring, holding the wastegate shut. I haven’t found the logger variable that reports the duty cycle of the control valve… that’s the first step. The second step is figuring out why it’s (presumably) not changing in response to the MAP drop. I sent off some plots and the tune to the ECU manufacturer so we’ll see what they say.