Heat shield barriers are designed to shield radiant heat. The tricky part to a heat shield barrier is that its heat reflectivity and reduction can change significantly with environmental conditions. You can take one product and have it drop 50% of radiant heat, change the environmental conditions (like distance to heat source and increased air flow), and have it now reduce over 90% of radiant heat. The trick here is, the more air flow and air space you get between the heat shield barrier and the heat source, the greater you improve the products performance. Most heat shield barriers require 1” of airspace; some do not so pay attention to the descriptions of products. Be creative; use a heat shield barrier to improve the performance of other components. Buy a cold air intake? Use a heat shield to turn it into a real cold air intake. Sleeve it, tape it, or stick it with a heat shield and knock those intake temps down even more. Got hot feet, stick a heatshield on the firewall, trans tunnel or above that catalytic convertor and muffler to keep you cool.