99 9-3S upgrade question

[redciv1]

I thought I remember reading this either on Central or over here on Link, however I saw where with my S model, if I were to increase the downpipe to 3" and then getting a bigger intercooler(maybe Viggen), that the increase in cooling air and bigger downpipe, would push the boost up to the t25's limit of nearly 14-15 psi without manually changing the boost.
The reason for asking is that I am thinking of making some upgrades, (bang for buck), and thought about getting a T28, 3" dp, and bigger intercooler, along with a ecu bump as well. Goal is around 300rwhp.