Hi HKS_TRD,
Yes this is possible. the way you go about achieving this will depend on whether you are using the fixed internal display layouts or if your C127 has Display Creator enabled.
I will provide an example of how you would do this in the fixed layouts.
First you will need to create a user condition which becomes true when boost pressure is > 0. This is done under Calculations>User Conditions. Exactly how you configure this will depend on the channels and data you have available to use for comparison but the output channel should be set up as On/Off data type. This can be created as a new channel. See example below

- Boost condition.JPG (40.01 KiB) Viewed 4183 times
After this open Display Setup, Functions>Display. Any channel position number with multiple spaces below it will allow for a primary channel with conditional channels configured below it. See below

- conditional channel.JPG (103.11 KiB) Viewed 4183 times
Configure the override so that the output channel of the user condition we previously created activates the condition, with boost pressure as the selected channel to appear when active below under settings. see example

- Boost display override.JPG (38.42 KiB) Viewed 4183 times
Let me know if you have any trouble with this.