I just did a full upgrade of my base e90 stereo using the alpine H660, which I think is completely under-rated. For the price you pay (~$220 for a brand new shipped), it cost about the same as the cleansweep, can do anti-EQ like the cleansweep and do most of the tuning by itself for a nice output.
Of course it cannot be compared to the tuning done by professionals at the workshop, but it sure comes close to it and tuning only takes a quick 15-20 mins if setup properly.
I have to say that the documentation is a shame. Even with the info I get from the different forums, my installer and I struggled to get the wiring right. But once properly wired and configured, the output is phenomenon. The MS-8 might be more popular in this forum as there are many core people in the forum driving it, but for less than half the price, the H660 gets my vote and I am loving it
