Here is a post from mazda.org, millenia section. this person installed a 2.3 in a protege, and was having problems with boost:
I think I figured out how it controls the boost; with the bypass open, it will boost to 0.5 bar, with it closed, 1 bar, it's as simple as that. I was skeptical when I read the jet chip can increase the boost, as the factory boost is already at the limit of the map sensor.
but if you are thinking about changing the size of the pulley to make the compressor spin faster, it wont work. since boost is controlled by the ecu/map sensor, you will have to modify that. dunno if something like a profec will work, but if it does, then you can probably increase boost without going to a different pulley. and that sucker is massive, and heavy, too. but if you increase boost, you will also have to increase fuel, and control/monitor timing, or engine go boom
