With all due respect, I think you are overlooking something very simple here…….. The turbo does not need to spin to create back pressure. The exhaust coming out of the motor is going into a very small turbine housing and in most cases on a Z32 going into a hole where the turbo wheel is that is less then 2 inches with a turbo wheel stuffed into it ? The fact that the engine has to breathe through this small hole creates more then enough backpressure for the low end response. I believe you are confusing some of your data. If you want to give me a call this afternoon, I will be happy to talk to you more about your data. Cheers!