Upper trim panel removed, revealing upper mounting screws. It appears that inner cage may be welded to outer cage [UPDATE: No, it just slides in, held by one screw at rear]. At the very least, the outer cage is slightly different than US/JDM:
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Close-up of right side. Car's radio harness hiding behind the metal face? [UPDATE: Yes, that's one of two]
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Removing the upper-left screw:
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Removing the lower screw (after removing the black plastic cover from the rear of the door):
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The owner wasn't able to remove the outer cage, probably due to the SVX's antenna wires (you need to unplug them first — connectors accessed behind the carpet on the left side of the transmission hump). See
section 2.3.2 in my SVX Audio Install Guide.