Buy a rule book for whomever you plan to run with before you do anything to your car if you plan to race it. For racing (auto-x and road racing at least) you need to build a car to the rules for the class/series you plan to run- the rules are probably more strict that you are anticipating.
I haven't run with SCCA in a while, and presently run with NASA. I cannot think of any series/class that will allow for anything but naturally aspirated vehicles (except for maybe one of the modified classes in auto-x, once again see rule book), which is why you probably won't find anyone who is seriously road racing who has a car with boost (lest its their street car and they have something else for competition)