I think you should consider contacting Clem. I've seen nothing but great reviews of his installs. I think he's located in Columbia MD.
http://www.e90post.com/forums/showthread.php?t=561186
http://www.e90post.com/forums/showthread.php?t=565780
I also recommend Induktion Motorsports for very reasonable pricing.
http://www.4induktion.com/index.htm