[Obioban]

Not to mention the issue of fitment. SS's bolt in like a factory part. My first (non SS) set of headers for my car rattled against the FCAB the entire time I owned them.

Evosport, which is a very reputable company in the BMW community (certainly more so than MMW, which has never made a BMW header as far as I know?), recently ran a group buy on a run of e46 M3 headers... most of which people returned because they couldn't get them to seal against the block.

There's lots involved in the design, and lots that can go wrong. For my money... SS is the only way I'd go. Some people would certainly rather spend less and it may work out fine. Or not. But that's not my preference.