8psi is a bit to high
Turbo Mini Forums

Fitted a boost gauge and a boost control value. I tried the car with boost all way down and it boosted to 8. Where was only getting about 4 psi before fitted the control value. Could there be a leak or some thing. I fitted the boost gauge on the hose that went to the old ecu is that the right way

Boost gauge should be connected to inlet manifold, otherwise you won't see vacuum, make sure it's not on the servo take off though as there is a 1 way valve on that. How have you Plumbed in the MBC?

If the pipe going to your boost controller is small, this can act like a restrictor and increase the boost as you describe.

In the 13's at last!.. Just