This was discussed in another previous thread on the N55 subforum:
http://www.f30post.com/forums/showthread.php?t=719670
Someone in the old thread commented that there is a different part number for the European M Performance exhaust and the US M Performance exhaust, I wonder if there are any design differences, like a quieter exhaust note, perhaps? Probably not, just wondering if there is logical reason to have a different European part number.
Regardless, the part number listed in the eBay listing matches the US part number listed on realOEM.com
US: 18302293774
European: 18302293773