Headers are an aftermarket performance product that replaces a factory exhaust manifold. Factory exhaust manifolds are often cast iron and log style leading to a very inefficient flow out of the engine. With a performance header the design uses a tubular format with a flange that attaches to the exhaust ports of the engine. By using a tubular header each cylinder has itís own exhaust pipe that flows into a collector and then sent back through the exhaust pipes. The most common types of aftermarket headers are made of mild steel or stainless steel tubing for the primary tubes along with flat flanges and possibly a larger diameter collector made of a similar material as the primaries. They may be coated with a ceramic-type finish (sometimes both inside and outside), or painted with a heat-resistant finish, or bare. Exhaust wrap can be wrapped completely around the manifold to improve efficiency by keeping the heat inside the header. Headers are one of the most important upgrade on naturally aspirated vehicles and create the most power once the full exhaust system upgrade is completed and proper ECU tuning applied.