I and no doubt others have weighed various bits, so if you search the forums there'll be some figures thrown up.
Think the sound deadening tar crap weighed about 14kg, and that was just what's on the floor. There's still the panels on roof and in the scuttle panel.
I've had my loom modified too, and had about 8kg stripped out, which includes the wires, connectors, and bits like the climate control panel, the clock unit.
Various brackets to remove all over the interior (but you may keep those if you're keeping seats.