Given enough digging nothing is invisible despite what some companies may say/advertise.If you remove it from your car is the dealership able to tell that you increased the boost? In other words does the computer keep a log of the max boost?
That said the dealership itself does not have the capability to dig that far down into the ECU. Nor would it be something they would be looking for in a service visit anyway. However, in the case of a catastrophic and costly failure (engine/transmission) a specialized tech will be brought in with more complex factory tools to diagnose and they can easily detect those types of changes. This is the case at least in the BMW world so it may be a bit different w/ Toyota -- not as familiar there.