I don't have DSP and ordered one where the install goes back to the CD changer (because I have bluetooth and BMW assist), and the install sounds very easy. Running the cable to a suitable location will be the hardest part...
Haven't received it yet since they are back ordered on the cable I need, but I'm anxiously awaiting it.

You could always buy it and take it to a car audio shop and I'm sure they would be happy to install it for you. Shouldn't be more than $200 to install.