TRD Supercharger 4.7 only 6psi?

[crushu]

I have fitted a TRD supercharger to my LX470. We have used an Xede ecu, and have not connected the little valve for the Boost Actuator, and have a vacuum line going to the top of the actuator, holding it where it is.

Boost with the air box intact rises to 5psi, then falls away. Boost with the air box open to atmosphere, goes straight to 6psi, and stays there all the way to top power. That shows that it isn't a blower speed problem, nor a leaking gasket, nor an intake restriction, as either problem would cause the boost to rise and fall, like it did with the intake assembled.

What is holding it at 6psi max?

Thanks