Ive previously ran a tee and still have the gauge.i was running the 1st turbo up to 30 but reset at 26...second turbo around the same.any higher and all its blowing is really hot air.
How many kms has your engine and turbo done? Those little garretts arnt the strongest
You can also tap into the intercooler and get a reading there. But to answer your question the stock Hitachi turbo on the d22 usually is set to 15-16 psi. Fitting a manual boost controller will bring it up 3 psi above that.