Plastic metalization process is carried out by heating the aluminum to its melting point in a vacuum so that the atoms and molecules will be evaporate and stick on to the plastic surface. then forming thin layer accross its surface. PT. Tomoko Daya Perkasa is one of the companies who performs plastic metalization. https://www.roneverhart.com/MagnaFlow-2003-2006-Toyota-Corolla-Street-Series-Cat-Back-Performance-Exhaust-System/