the problem with a loc or clean sweep or 3sixty, etc. is that you are still dependent upon the factory head unit for your source, and that can really have a negative impact on sound quality, and gives you few options for tuning. I plan on getting an aftermarket hu, I just wish there was a double din opening for a large touchscreen. I guess I'll have to go with a single din (avic-n4, alpine d105) although it doesn't lead to the cleanest look.
check out this thread on an install done in a 335i:
http://www.e90post.com/forums/showthread.php?t=78107
