Hey thanks for the response,

Should have been a bit more specific and said it's an intake manifold for quad throttle bodies for which mild steel would be fine.

Can you weld 304 with a suitable gassless wire (nickel?) or would I have to go buy some gas as well for my MIG. Hard to weld or similar to carbon steel? I guess there's a bit of an advantage in slowing heat transfer with SS, although the flange is mild steel. (Pretty sure nickel lets you weld them together.)

316 would be the go if I was going to cook on it or piss on it , or if I lived next to the ocean. (Paint's probably cheaper.)

I'm half thinking about chrome plating after I've built it, only because my partners old man works in that industry, paint would probably do the job.

will look about. An exhaust manifold is on the future project list so they're also helpful tips.