So, setting the cancer aside, what are your plans for insulation?

Last year, I helped a friend line his wife's mx5 with "Reflectix" on the floor and transmission tunnel. The material is like a thick, metallic bubble wrap. It cut down on the internal cabin temps by quite a bit, but didn't do much for noise. My other concern with it is that if the cabin gets wet the plastic might not be breathable enough to dry properly.