Dynamat is a name-brand product used to insulate car panels and placed in areas such as the boot to reduce vibrations created by car audio systems and external noise. Dynamat is sold by the square foot, and it is fairly expensive, especially when it is installed in large portions of the car -- such as in the boot. There are several different products and alternative mats that can be used instead of Dynamat that will produce similar results.
One alternative product is Ice Guard, which is sold as a weather guard for roofing material. Purchased at any big box hardware store, Ice Guard can be 80 per cent less expensive than Dynamat. The main difference between Ice Guard and Dynamat is that Ice Guard uses an asphalt material for water proofing. Because of this, Ice Guard can be very messy. After installing the material in your car, it needs several days to be exposed to air. Charcoal powder or baking soda should be applied to it before carpet is reinstalled. There are other name-brand products that are similar to Ice Guard, such as Brown Bread. The major downside to brown bread is that in high temperatures the asphalt side may melt in the heat, making it not safe to use in some portions of a car.
Foam pads, similar to matting, and spray foams are both used to soundproof cars. Foam pads are used in a similar fashion to Dynamat and are laid down over panels to reduce vibrations. Sprays are used to coat or fill hard-to-reach crevices that mats or pads cannot effectively cover. As the spray foam drys, it slightly expands, covering the entire area over which it is applied. Styrofoam (polystyrene foam) can be purchased in a spray can. But a more environmentally friendly and cheaper version is Great Stuff, which is used to insulate homes.
The same type of insulation used underneath carpeting in your home to give it some padding can be used under the carpeting in your car to reduce sound vibrations. Jute is the most common type of insulation used under carpets, but micro jute, a thinner version, is just as effective and fits better into cars. This material can be purchased at any carpeting store and is less messy than sprays or foams and weather shielding.