Quote:
Originally Posted by KingLT1
Certain types of Stainless will in fact show surface rust. Flowmaster uses that type of stainless(409). It's not pure stainless...a magnet will stick to the mufflers and pipe but not the tips.
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Tips are 304, rest of Exhaust is 409S
Most modern factory exhaust systems are made from 409 stainless steel. It is strong and will last 8-10 years in a moderate climate. 409 stainless steel will rust on the surface. However, this is not a concern for most people because it is hidden under the vehicle. Surface rust can be cleaned with a wire brush.
304 stainless is the highest quality material used for exhaust parts. It will last 10 years or more in a moderate climate. However, it is the most expensive. It will not rust for many years. But, it will turn a golden brown color after being exposed to heat.