As I'm sure most of you know, the stock audio system is garbage. I can't turn up anything without hearing pretty bad clipping. I'm not trying to get my Mini to bump (and I want to keep all my cargo space) so I don't plan to add a subwoofer, so I guess my question would be:

What's would be needed to upgrade the amp and component speakers in my Nav equipped R56? Any particular brands that people have had good luck with in the car?

I would also like to make the install as clean and stealth as possible so:

Where are some good tried and true amp mounting points?
Are there any factory replacement pieces that will allow me to add tweeters so that they look factory?

Thanks in advance for the responses.