1. The European / UK "included" EVSE is L2 (220/240v) not L1 (120v).
2. After this mod to the USA "included" L1 EVSE, it becomes a "universal voltage" (L1/L2) EVSE.
3. This L1/L2 EVSE would still "offer" 12 amps Max to the car, I believe.
4. It is likely that there is more to this "mod" than just replacing a component and the "waterproof" pigtail.
5. Getting the mod and adapters done RIGHT is certainly worth something!
6. Wattage:
120v x 12a = 1440 watts (standard L1 EVSE)
240v x 12 amps = 2880 watts (L1/L2 EVSE)
220v x 15a = 3300 watts (3.3 kW "nominal" EVSE description)
240 x 16 amps = 3840 watts (3.84 kW, a 16-amp L2 EVSE)
7. Useful Pigtails:
a. for 120v socket.
b. for 240v 4-pin (modern) dryer socket.
c. for RV "30-amp" (120v) socket
d. for RV "50-amp" (240v) socket
e. Others