I hear some people saying it's safe to turn up boost 1-2 psi without any other mods... anyone know for sure? that would make it at 20-21 psi total.

 

it also depends on the turbo's efficieny. if you looks at graphs of a turbo's hp output versus airflow there is an ellipse that determines the ideal efficiency range for that particular turbo. if you crank the boost up too high, you will be outside the efficiency range, likewise if the boost is too low. therefore, you will generally make more horsepower with good tuning running appropriate boost, than you would by just "turning up the boost". for example, if i am running stock boost (19.5psi) with a good tune, and i race someone who just cranked up the boost to 22psi, i will win. Just because the pressure reading is higher does not nessitate that the horsepower output will follow suit.

 

ahh.. thanks for the input en1gma19