I have an 06 E85 Z4 3.0i with std Hi-Fi and I'm looking to add Bluetooth / iPod. Bavsound offers the Soundplicity upgrade - has anyone done this? Is it any good? What are the simple alternatives, if any? From what I've read here and in other forums, it seems replacing the Business CD head isn't a simple operation with integration to the existing amp. Have things changed in the last couple of years with newer head units? Has anyone upgraded speakers from Bavsound? Are they much better? (I realize there have been a number of similar posts over the years, I'm hoping someone has recent experience of doing this).