Bought 2 models for our entrance bedrooms as we are on a noisy primary road. Set up them yesterday and the real difference in noise is awesome. I went for your six.4mm laminated glass and positioned the models on the entrance with the window sill to provide highest gap. https://howtodoperfecteyebrowshap98641.blogolize.com/double-glazing-alternative-fundamentals-explained-73658518