Bolting on a performance exhaust system adds an exciting new tone to your car. But, that sweet song becomes annoying noise as corrosion eats away at your exhaust. If you want the music to last, start with steel that’s designed to outlive your car. Water is the natural enemy of an unprotected exhaust system. During proper combustion, water droplets form and drip from the tailpipe. Most of the water is forced out by the exhaust but a fraction of it stays behind—and, moisture and metal don’t mix. This excess water gradually turns your shiny exhaust into ugly-rust from the inside out.
What Does Stainless Actually Mean?
Stainless steel exhaust components stop your pipes from corroding. But, not all steel is created equal. You see, some alloys corrode over time despite the name “stainless”. It doesn’t necessarily mean “stain proof”. Corrosion resistance depends on the content of chromium and nickel found in the alloy.
What’s Better, T409 or T304 Stainless Steel Exhaust Components?
The most frequently used stainless steel in performance exhaust system is T409. Found in Gibson exhaust and many stainless mufflers, this mixture has enough chromium and nickel to resist corrosion. But, it lacks the strength to be used for fasteners. Next up in the ring for corrosion resistance and all-around toughness is the T304 steel used in Borla exhaust headers and Corsa exhaust. This is the highest quality stainless steel used in the automotive world. It is most often found in exhaust tips. Super tough and nearly impervious to rusting, T304 has around 20% chromium and 10% nickel content in the alloy. In fact, the ferrous metal content is so low that magnets won’t stick to it, making identifying T409 from T304 very easy.
Making the Right Exhaust Choice
In short, when comparing T304 vs. T409, the best choice is T304. But, both alloys far surpass aluminized steel used in factory exhaust systems. There really is no wrong way to go as both a T409 and a T304 exhaust system greatly improves your vehicle’s performance. If deciding between the two choices is corroding your confidence, check out our exhaust system reviews, and see what these kits are really made of. Or, feel free to leave a comment below.