No two vehicles are exactly alike, so it is impossible to assign specific numbers of horsepower or torque. In general, though, a set of performance exhaust headers will unlock around an extra 5-25 horsepower along with a noticeable boost in rear-wheel torque.
Performance exhaust headers absorb some of the most punishing abuse of any part on your vehicle. They are constantly being cooked at temperatures of around 500 degrees Fahrenheit, and time will eventually take its toll on any finish. Performance exhaust headers with a ceramic coating are the most resilient and will retain their finish the longest. Stainless steel is also incredibly durable, but it will start to tinge slightly after a while. Nickel-chrome will also change color, especially if used for racing or towing. High-temperature paint usually stays the same, but it can be chipped.
However, discoloration does not affect the performance of your exhaust headers. They still work just the same on the inside no matter how they look on the outside.
It depends on which performance exhaust headers you get and which state you live in. Most of the headers at AutoAnything are 50-state street legal, which means that they don't interfere with pollution-controls on your vehicle. A few of our headers are designed for off-road or racing vehicles that are exempt from smog certification, so they are not street-legal. Then again, some states have more relaxed pollution controls than others, so a set of off-road headers in California might be street-legal in Montana.
If your state requires that you pass a smog test, get a set of headers that are 50-state street legal. If not, then they sky's the limit.
Not necessarily. Thanks to the Magnuson Moss Warranty Act of 1975, vehicle manufacturers cannot refuse to perform repairs just because you have installed performance parts. However, if they can prove that the part itself contributed to the problem, or if your warranty expressly prohibits performance upgrades, then they can refuse to honor the warranty. Always take the time to read your warranty before installing any aftermarket parts.