Reignman

I am going to start tuning my new turbo soon and I have a questions about the Greddy E-Manage. I see that the injection and timing control maps are based on RPM vs MAP sensor voltage. I am going to set it so that the MAP sensor is clamped at 2.9v so that the ECU wont see the boost but how will I be able to tune over 2.9v if it is clamped there?

Thanks