if you have a single turbo like a T3 or a T4 then they normally have an external wastegate and the boost is controlled by the wastegate spring and you connect a vacuum line from the front of the turbo to the wastegate. The ecu does not control the boost when you go single turbo so basically on any na-t its mechanically controlled by the wastegate. the tt ecu does not care it just sees what psi you are at via the map senor and its happy as long as you dont hit boost cut.
For example, I have a 9 psi wastegate spring in my car. with just the vacuum line from front of turbo to wastegate, my car will boost to 9 psi and then hold right there.
to get more boost, you can run a boost controller, for example I have a manual boost controller inline on that vacuum line, and if I turn the knob on it it will raise the boost level, usually I have it set to 18 psi. so the car will boost to 18 and then hold.
The TT ecu has a factory boost cut at around 14 psi (at sea level) or like 16 psi if you are at an elevation like me (Denver is a mile above sea level).
so if you plan on booting more than tht, you need a boost cut controller (like greddy) but be careful cause this removes it completely, so if something goes wrong and you overboost (like the wastegate vacuum line melts of comes off) ten you are on your own to let off the gas to save the engine when you overboost to 20 psi in a second or so...
or you can also bypass boost cut with a piggyback and larger injectors like I run the map ecu with 550cc injectors and it gets rid of boost cut and actually lets me set where the I want it, so I have my boost cut set to 20 psi cause I run 18 psi, so if something goes wrong and I build more than 20 psi boost cut kicks in and saves the engine. I prefer using the map ecu because of this. the emanage can do similar I want to say, even the aem fic. you can even raise boost cut with an safc, but its not as clear cut.