Hi,
That is the correct foil for the boat. The only other foil that exists is for the Nacra 6.0NA (also used to convert a Nacra 5.8 to a Ncra 5.8NA), which is not correct for your boat.

If not using the jib, take the advice above.

Good luck

Steve
Hobie FX-1, Sail #211
(Former owner of 1993 and 1998 Nacra 5.5SL).