mmmmmm when I did my exhaust, the guy told me all oem came with mild steel but mufflers on higher end cars could be stainless....but he's an old fart....who knows haha....but he pointed out that the big selling point of stainless was the durability and how it looks....and then proceeded to a 2 min swearing diarrhoea of who the hell looks under their cars to look at how nice looking the exhaust pipes are. And then he made a good point of if oem exhaust can last 10 years without the rust creating a hole, why do people need to pay extra to get stainless...