Far canal - those prices are crazy. If it were my neighbours I'd say stuff 'em as their bloody yappy dogs go all night - so I'd see it as payback.
I've looked into a Remus but they don't have a specific one for the E90 - the E92 one can be modified but it seems like a bit of a hassle. At this stage I'm waiting for an E90 model. I also chose Remus as the Sport system is ADR and not so loud as to attract a yellow sticker!
2012 BMW F10 520d M-Sport
2010 BMW E70 X5 xdrive40d