Anyone knows where I can buy some metric stainless exhaust tubes in 60mm diameter?

My local performance shop can have some stainless steel tubes from Magnaflow I think, but it is 'exhaust quality' he says, if you put a magnet to it, it will stick and with time, will develop surface rust, and, it is only available in SAE sizes, no metric. The only other option is 304 SS but it is a polished tube, for show cars.

I would like to find something like BMW OE, good quality stainless, but not polished (no need for 304 SS).

I'm ready to remove my resonator and replace it with a H-pipe, and don't want to install a piece of tube that will rust.

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