Yes thats the part

 

Can you use the Dension product with the 997.1 and get a direct fiber optic link that will improve sound quality?

 

For the money you will pay for the Dension + if you want to add Bluetooth you are better of spending a little more to get a new HU like the Avic z120BT. You can bypass the crappy bose amps, get Ipod connectivity, Bluetooth, a sweet HU with touch screen, great Nav, and your sound will improve exponentially. Search the threads and you will see and hear form people that have done it. I am in the process now. Waiting for the components

 

It does improve it quite a bit. If you use higher rez files on your ipod, I've found pretty decent quality. The highes from the Bose system are still far from what I'd like, but I don't want to mess around with a non-stock look (I've also got a multi function wheel). Depends a bit on your budget. The Dension is a DIY and a reasonable way to go.