[ctuna]

You need to identify your system
if you have a US 08 it will be either Hi Fi or
L7 what it says on the Head Unit only has to do with
the model of the Head Unit.
And the under seats should be working with either of those systems.
Although they are pretty weak with the Hi Fi.

BMW stereo types
http://www.e90post.com/forums/showthread.php?t=352586
http://www.e90post.com/forums/attach...2&d=1266451970
http://www.e90post.com/forums/attach...2&d=1260829447
http://www.e90post.com/forums/showthread.php?t=343673
http://www.e90post.com/forums/showthread.php?t=138949
http://www.e90post.com/forums/attach...1&d=1209780605
http://www.e90post.com/forums/showthread.php?t=641323
http://bmwcoders.com/forum/3-er-8/bm...1-e92-e93-291/
http://www.e90post.com/forums/attach...1&d=1209780865
http://www.google.com/url?sa=t&rct=j...,d.cGU&cad=rja
http://www.musicarnw.com/page-2/
http://www.e90post.com/forums/attach...4&d=1278871872

How did you add the sub would be the first question?
And were they working before would the next?