Me agiain!

I just bought a new set of BOSCH GREEN 803 injectors (new 167 pounds) my question is the car apparently has a BBR 2 stage boost 10 psi /20psi set up, it has a small switch on the dash that indeed seems to swith between 10 and around 19psi, how does this work? is the switch liked into the chip installed into the ecu? or is it a boost controller (i.e 2 stage bleed valve type thing) my intention is to fit a 3 bar map sensor along with the new injectors and a stage three chip. i asume i need to get the current BBR conversion removed and start again? how is the boost controlled? is it by adusting the acuator arm?
Or ......could i fit a new chip/Injectors/map sensor and still run the bbr conversion, then just adjust the actator arm to run say 23psi?
Thanks Peter