"The N-75 has a few variants that define the responsiveness of the solenoid to the voltage signal. N-75C, N-75F, N-75H and so on. Slow response variants cause higher boost spikes at partial throttle. Faster response will be lower and smoother at PT."
I'm not sure which variant I have. But my concern was not about boost spikes or transients related to the solenoid valve, it's about steady state boost level. I don't recall seeing any boost spikes from the valve, and even if they were there, they would have been short lived. What I was trying to do was restrict steady state boost so that I had much less than full boost when I was much less than full throttle. I don't know why I (or anyone) would ever want full boost at anything less than full throttle. But I definitely get full boost way before full throttle. Or at least, I get way more boost than I want or can use. Accurate control of the wastegate -- and ultimately boost level -- (especially with a big turbo like mine) may not be easy to do with any type of available hardware or tuning regimen. If anyone has any ideas, I'm very open to hearing them.