debtxpert, welcome to the forum!
I have an E92 335i with the dealer-installed iPod adapter (better known as MOST iPod adapter).
It's okay... if you have lots of playlists and if you maintain your playlists. It loads the playlists instantly, however, if you want to search using a different view (artist, genre, etc...) it is slow. When turning it on, it will default to playlists, and usually loads within a few seconds. When changing to sort by artist, it takes longer if you have more artists. Mine takes at least 3 minutes to load. Furthermore, there is a 500 listing limit, so my artists only load to the letter "L".
I too have the "too much bass" problem with my iPod. So, for me to play normally, I have to lower the bass to the minimum.
If you are not busy Saturday, please come out to the BIG SoCal E90/91/92/93 meet in Fountain Valley. You can get lots of ideas and meet others who also have the mod bug.
http://www.socale90.com/forums/showthread.php?t=291
Here is the info:
Mile Square Park
16801 Euclid
Fountain Valley, CA 92708