Boost isn't ECU controlled on a G40, so it's a case of fitting a smaller 'charger pulley and/or porting the 'charger for higher boost and then tweaking fuel and ignition parameters in the map to suit.
Rather than flash programming the ECU's memory via the diagnostic port like you would on ME7 on a 20v, with Digifant you physically remove an EPROM chip and swap it for one with altered parameters. Both some of the control software and the calibration (or 'maps') are stored on the same chip in G40's Digifant ECU.
When live mapping a G40 ECU, the chip is removed and replaced with a cable which links the ECU to a laptop via an emulator. The emulator's job is to behave like the chip to keep the ECU happy, all whilst talking to the laptop and allowing live editing of the chip parameters.
Whilst Digifant is a whole lot simpler and less powerful than modern ECUs, it still does the basics as well if not better than a lot of aftermarket systems.
