A careful study of CSC website and email with questions reveals RX4 does not come with cases. Choose composite with small or large top cases, Tourfellas, same for RX3, but no answer to direct question if RX3 racks fit RX4. However, t
his page shows all hard luggage options fitting RX3 and RX4.
CSC also has
soft luggage which I suspect will fit racks for either hard luggage option. CSC does list the Tourfella pannier racks for the RX3 and RX4 on the soft luggage page, and the top rack is a separate purchase on the hard luggage page. Each rack and Tourfella case can now be bought separate. That would have saved me $600 after that $^$%^ yankee in a speeding truck in Illinois gave me that blow job a few years back.
Now, it is possible that these racks and hard panniers are a new design and the old set, if different, may not fit the RX4. I want an RX4, and need only one pannier to have a full set of Tourfellas, but I'm not spending money if I have to buy a whole another set of racks. The RX4 has a bunch of extras I don't want, like power outlets and such, so a cleaner Japanese motorcycle without all the extras to go wrong won't cost much more than the otherwise overpriced for my needs RX4 to which I'll have to add the high dollars for yet another set of Tourfellas.