My boost gauge works in BAR....I wish it worked in PSI!
When I started configuring my boost controller, I set the ratio to 10 (according to the manual this is 10% of maximum boost - which is bollocks BTW) and my gain at 5.
I then went on the road, held the revs at 4.5k in third gear and then floored it. I took note of what boost pressure I was getting i.e 0.35bar and then I would increase the ratio by 5 and then rinse and repeat. This gave me a clear idea of what boost pressure was being acheived with what ratio.
Do this in your car, take note of the PEAK boost achieved in each run and then adjust your settings upwards until you are happy with what you have.
First time I did this, I didn't fully understand the ratio and my first run peaked at 1.1bar!!
on high boost setting, my car peaks at about 0.85 bar, and rarely spikes above this - though it does occasionaly happen with a pedal to the floor 1st to seond gear change......but then I have it set to drop the boost if this happens.