Why do people make a nice shiny stailness steel exhaust system and then put mild steel flanges on it?
Is there some reason that I am not aware of that makes mild steel flanges preferable?

Im guessing a mild steel flange is a LOT cheaper than a stainless one?

machining stainless is a pain.

a lot of manifold guys grind the header flange flat with a long belt sander .

theyre reputed to be able to pull studs out of heads from distortion when hot also , altho ive never seen it in person.

I needed some machining done to mine after welding, it kept chewing up his milling cutters. Once he'd done it he told me he never wanted to see it again lol