What boost to run?

Another noob here! Sorry, I couldn’t find a similar post to answer my question. I’m sure theres one, but I just can’t find it.

The battery in my 13 went dead over the winter and I assume this reset the pre-set’s on the gfb boost controller, as the boost has now halved (I can’t think of any other reason) I need to set boost controller back up, but I’m not sure what boost to run.

Spec is a CA18, with uprated injectors, T28 turbo, Walbro pump, fmic, and a stage 2 h-dev chip running 280 on the dyno.

Could anyone suggest what boost I should sensible run? And if possible the gain and sensitivity on the g-force 2 controller.

Thanks!