(1) will the SWMotech, Givi, etc side mounts work if I replace the big Kawasaki cans with the smaller Yosh cans?
The side cases will fit with any mufflers. The OEM mufflers will need to be lowered a little bit. My Muzzys fit with no lowering required, and while I can't speak for every aftermarket muffler make/model, I would guess that since most or all seem to be smaller than OEM, probably most or all of them would also not need to be lowered. That said, lowering them is not a big deal: Either purchase or fab up a short strap of steel or aluminum to insert at the muffler's rear foot peg mount point that lowers the muffler an inch or so, just enough so there's a little space between the top of the muffler and the bottom of your loaded side cases.
And, regarding hard top cases their seems to be a footnote on the websites about needing to replace the rear cover panel, which is a Kawasaki rear cover panel, something about difference between US and European models zx14's. Can anyone confirm that are is there perhaps and easier work around?
I didn't purchase the piece SteveStLaurent did. It's been a few years since I did it, so I'd have to look again to explain it precisely, but I seem to remember that I decided trimming my OEM to fit around the top case mounting bracket would be fine for me since with a top case mounted you can't see into that area well enough for it to matter much. I'll try to take a couple pics of mine tonight and post them.
=x+rap01a+0r