I don't believe it's emissions, but rather noise restriction. There are a few threads covering this and how there are two exhaust systems on the 1m, Chinese market and non-Chinese. Very unfortunate, but not irreversible.
2011 E90 M3 ZCP/AW/Ohlins R&T/Vorshlag CP/Stoptech ST-40 Trophy Street
2011 1 Series M Coupe/VO/Fully Loaded/Bloated