Nothing. The EFI system has a fuel table calibration range of 20%. Pipes easily fall within that.
As you ride it will self tune, and adjust where needed.
Ideally, after ~50 miles you would Merge the learned maps to write them permanently into the ECU so you don't loose them if you loose battery power.
Did some research and found out that they do indeed have 18mm wideband o2 sensors so you would have to have efi pipes with the bungs installed to accept the o2 sensors or you could weld the bungs on and drill out the carb pipes. You do have to have the o2 sensors for the auto tune to function.
You won't need a Fuelpak on a Big Dog, it is a wideband system that will auto tune within 28% of the fuel table. You should be well within that parameter with just changing the pipes. Harley's are a narrow band or closed system that will not auto tune and you need a piggyback tuner like a fuelpak to add or subtract fuel from the base table.