Another thing to check before you buy a GRP4 steering coupling.
There are two inner steering column lengths, 96cm & 100cm, you'll need a long coupling for the shorter column, or a short coupling for the longer column.
If your WCXM has a lower steering rack mount (the GRP4 Fabrications version does, although it's not mentioned in the specs when you buy it), you'll most likely need the longer coupling even if you have the 100cm long inner steering coulumn. . . which I recently found out for myself.
Cheers,
Jason.