Quote:
Originally Posted by sc2dave
WRONG!!!! Headers do not make it hot enough to damage cats. Cats get damaged by unburned gas that burns in the cat and eventually melts the insides,destroying the cat.
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I'm sorry, but I'm going to have to default to what I have been told by professional mechanics and aftermarket tuners. The ceramic catalytic converters provided in OEM exhausts are designed to operate within specific temperature ranges, and if they are subjected to excessive heat, they will break down and fail. Typically, that increased EGT is the result of leaning out the AFR, but it can also result from changing the structure of the exhaust system. A typical exhaust manifold is cast out of iron, which means two things: One, it has more mass, meaning it can absorb more exhaust heat. Two, the stock exhaust manifold has a larger surface area, meaning it disperses the heat better. Headers have possibly 50% or less mass than the OEM manifold, and, while they do flow better, that only means that the hotter exhaust gets to the cat even faster.