When it comes to adding power to your Tundra, replacing your stock exhaust manifolds with headers is an option worth exploring. Stock exhaust manifolds are typically designed with low cost in mind, and on many vehicles they are restrictive and inefficient when compared to after-market headers. On most vehicles, replacing the stock exhaust manifold with headers will remove flow restrictions inherent in the standard system and scavenge as much exhaust gas as possible out of the engine. For most trucks (especially trucks made more than 5 years ago), headers are a great way to add decent power to a stock engine.
However, fans of the 2nd-generation Tundra know that the stock exhaust manifold on the 4.6L and 5.7L Tundra is actually quite good. In fact, the stock exhaust manifold on newer Tundra trucks is one of the more sophisticated factory exhaust manifolds you’ll find. They’re an efficient stainless steel 4 into 2 into 1 design, a configuration that’s known for moving exhaust gases quickly. The Tundra’s stock exhaust manifold tubes are also equal length for each cylinder. Equal length tubes are important because they facilitate consistent back pressure in each cylinder, improving overall performance.
The bottom line for 2nd-gen Tundra owners (07′ and up models) is that replacing the standard exhaust manifold with a set of less restrictive after-market headers isn’t going to result in huge gains. Still, that’s not to say that adding headers to a Tundra will have no impact.