[Shane@DBPerformance]

You try to keep it at one boost level and tune it for that setting. If you plan on running different boost levels and different fuels, then people will usually either write down the settings and manually put them into something like an S-AFC when they change the boost. Or if their tuning device can hook up to a laptop, then they just save different maps and load then in as needed. There usually isn't any reason to run less boost than your car can safely handle on a specific fuel. If you don't need to go as fast or don't want to waste as much gas, then you just don't push the throttle pedal down as far.