Just wondering if they're not, besides the magnet test, is there a way to tell like part number or some other method.

yes they all are as far as i know.

Cool, thanks.

No not all.

If you are aware of any that are not stainless then please explain. I believe that all 496 risers (merc) are indeed stainless. Older manifolds are alum. Newer manifolds are cast.

Not all aftermarket risers or headers for the 496 are stainless. If you ment Merc OE only then as far as I know always stainless risers.

If they were stainless, why would they paint them? Mine are either painted, or powder coated.

Cheaper than polishing and Merc likes things black is a guess. They are stainless.

That's a great question Dave. After a little rubbin' mine aren't painted anymore.

I polished mine now I haveCMIs