The "base" system is fairly rare in BMWs: only 2010 and early 2011. So the OP may indeed have the base system. But there are several opinions expressed here; it may be possible that there is confusion between "base" and "hifi". You may want to go here:
http://www.e90post.com/forums/showthread.php?t=641323 to find what you really have.
FYI, I have/had the base system in my 2010, but have done the Alpine upgrade path and now have essentially the HiFi system (actually a bit better since it has better speakers than the original OEM HiFi.) BMW was doing a cost-cutting ant thought it could sneak in a really awful system.