Has anyone ever attempted a base audio system upgrade to the Hifi or Premium system using all OEM parts?

I recently purchased a 2010 x5 35d which I love, but I noticed the speakers felt REALLY flat - my 99 e46 has a killer system in comparison. Some quick investigating and WOW - BMW really crapped the bed when it came to the base system. So I started investigating..

I understand that you can recode the head-unit to Hifi (I'm not sure about Premium though -- there's different hardware involved?). Aside from the recode, you would simply need to purchase speakers, some wiring harnesses and the appropriate door panels, right?

It would be nice to have more and BETTER speakers than what I'm running now and to keep everything as clean as possible. I'm new to this forum and it's slightly difficult to find information since all e70 information is all in one "section"... I've searched, but have found little that is too straightforward except for the BSW state-1 kit

Brad
'83 320i 292k
'99 323i 192k
'10 X5 35d 18k