My 04 TL stock system is great,, I see no need to upgrade, but then I have no intentions of playing DVDs or games in the car.. for just audio it is fine the way it is.. Although I think TLs with Navi already can play DVDs. I know the stock system is surround sound compatible and already has a fair sub-woofer.

And the tweeters are great, the overall range is great.. I tend to listen to mostly Jazz, but also listen to Rock and Classical and oldies.. I love the XM raido,, quality is as good as listening to a CD. I just got the two disk set "The Esential Santana" and it sounds better in the TL then on my home stereo.