PST FTN

The greatest gains will come from replacing the engine’s stock exhaust manifolds with headers. “Original-equipment exhaust manifolds tend to compromise combustion efficiency primarily because the factory needs to design vehicles for a very wide range of applications’ says Steven Anderson, special-accounts manager for Flowmaster, an aftermarket muffler company. “When it comes to the specific uses that interest your guys—for example, heavy hauling, towing, low- range four-wheel-drive, and higb-altitude operation—the factory manifolds can work against you. But aftermarket headers can change that.”
What exactly do headers do?
“One of the biggest obstacles to better performance is back pressure, which is the unwanted result of the system’s inability to remove sufficient spent gas,” says Anderson. “Back pressure causes some of the restriction in exhaust gas flow, as does the design of the stock manifold itself Typically, a properly designed header is an arrangement of individual pipes that lead from the exhaust ports into a common passage, which eventually enters a muffler. Exact pipe size and length not only help determine how much but where in an engine’s rpm range power improvements are provided. Obviously, for trucks it needs to be in the lower range, below 4,500 rpm, where sportsmen need it most.”
So, bottom line, headers, when properly tuned, help improve overall combustion efficiency. And that, ultimately, is interpreted as seat-of-the-pants performance. But there’s something else as well. Headers can lower the underhood temperature, and that can help extend engine life.