For all of you out there who own the fiber-optically controlled YS90-DX strobe, here's a little hack I think some of you might find useful.
I started off with the diffuser panel that Sea & Sea forgot to incorporate the fiber-optic holder into it. I used my trusty ol' Dremel to cut 'HORIZONTALLY' the center of the diffuser..

This leaves you with a piece that looks like this:

Clean up the edges a bit and then simply drop it into place:

Now put the fiber-optic holder back in place over the cut diffuser panel. It will lock into place without any problems and keep the diffuser panel from coming out or sliding around.

Barabing Barabung!! An easily removable diffuser panel for your YS90DX. The final work looks real clean as the cut edges hide behind the fiber-optic thingamajig.
The final setup in Muppet Vision 3D:

The difference a diffuser panel will make.. a wider beam and a lower color temperature of 5100ºK from 5500ºK. From a non-scientific point of view (that would be mine) I find it easier to keep my photos from blowing out the highlights and supposedly the strobe light covers a larger area.