Read FIA Rally2 technical rules or Skoda has done it easier..

It(engine) is based on the 2.0 TSI production engine from the EA888 family, used for example in the Octavia and Kodiaq RS. The obligation to base the engine on the series engine applies to all Rally2 class cars, as does the defined supercharged power unit capacity (1.6 litres) or the use of a 32 mm diameter intake restrictor.