The only way I can figure out that how it works is that (just throwing number out, too lazy for real math and yes, stock TIP is 3bar, map 2 bar so voltages would be different) is that when the map/tip should be sending a ~4.0v signal, the boost max lowers the voltage (only forwards say ~3.0v), tricking the computer into trying to compensate. It only ties into the MAP, TIP, and TPS so yes, it is going to skew tq/load calcs for sure.
Edit: looking over the install instructions it ties into the Pedal Position sensor under the dash, not the TPS sensors on the throttle body.