there are many options to go. you can choose to remove the dsp as
"el duderino" has done a write up on how to bypasss the DSP. but that would require a skilled installer who has worked on BMW's . or if you want to retain the dsp amp Rockford Fosagte has a new piece that will integrate with the oem factory amp called the 3sixty.

http://www.crutchfield.com/S-Nwlb81o...5753SIXTY1#Tab