If you are using a Bombora X-it, then you are probably also using a similar generation sail.

Old sails often produced a lot of power, but weren't as good at efficiency -> as such, they didn't feel as good as a modern sail of similar size. Relatedly, often a modern sail will need more sail area to have the same power, but will be much more efficient once planing. As a side benefit, modern sails will be easier to sail, lighter weight, and probably be useable in a wider wind range (aka you could use the larger size, when you normally consider using the smaller size).

To answer your question, most people have between 0.5m to 1.5m speration between sails, with less separation for smaller sails, bigger seperation for larger sails. For a 5.6, you could expect to move up to a 6.5 or so (with the caveat of the previous paragraph).

Thanks
i'll keep my eye out for a 6.5

yeah i dont get many strong winds. its always in the 15 knot range and its hard to learn to carve when youre not going fast enough

I'm pretty sure that board can take up to a 7m, which should be a fine gap from a 5.6m, and maximise your wind range. So something 6.5 to 7m is prob the way to go.