GMC S15 Header is the term used to describe the aftermarket product that replaces the factory exhaust manifold. Headers are normally designed to be less restrictive than the factory exhaust manifolds that they replace, thereby generating more horsepower.

Headers are considered part of the exhaust system of the vehicle. Right after the incoming air and fuel combust, the result exhaust is push through the headers and out the exhaust. The headers are often connected to the catalytic converter, which is connected to the muffler and exhaust tip, so the headers are the "front" of the exhaust system.

Some of the popular brands of headers that you'll find are: DC Sports, Hedman, Hooker, Doug Thorley, Pacesetter, and Flowtech, among others.

We get asked a lot if you can buy GMC S15 headers but still leave the stock catalytic converter in place. The answer is yes in almost every case, as the GMC S15 headers are still designed with flanges in most cases that will mount right up to the existing factory parts.

Q: What are the different tubing options for headers and what is the difference between them?
A: There are two major designs for headers: the 4-2-1 design and the 4-1 design. In many cases 4-1 headers are designed for racing applications where the vehicle is being driven at or near redline. The 4-1 design maximizes top end power, whereas the 4-2-1 evenly distributes it throughout the power band. Either way, you're going to be getting more horsepower from a header.

Q: What does a header do? Why buy a header?
A: An exhaust header is a performance product that replaces your factory exhaust manifold and improves an engine's performance by allowing air to flow more freely. The easier an engine breathes the more power it produces. Headers generally use piping with a wider diameter than factory tubing, which allows more air to pass through the exhaust system than factory. A header is one of the easiest bolt-on modifications you can make to increase horsepower, making an effective use of money if your goal is to quickly gain horsepower.

Q: How do you install a header?
A: A header is a direct bolt-on. Simply remove the factory OEM exhaust manifold and the aftermarket header is put in its place. The header is to be attached the head of your vehicle. Remove all the bolts that hold the flanges in place and detach the factory manifold. The down pipe or exhaust pipe should be removed as well and then reattached once the header flanges are bolted back onto the head.

Q: For which vehicles is it necessary to buy a pair of headers? On your website are headers automatically sold in pairs for these vehicles?
A: When purchasing exhaust headers for a V-6 or V-8 engine, the header package is complete with two headers. If your vehicle is a 4-cylinder, there only a single header that is used.

Q: How much does the material used to make the header matter?
A: There are two main materials that headers are manufactured out of: ceramic and stainless steel. Ceramic headers are less expensive, but are prone to cracking if they get to be extremely hot. Stainless steel headers are more expensive but are more durable and generally more stylish. Stainless steel headers can take any kind of heat you throw at it and not prone to cracking.