Just bought a C6, and I have a few questions
 

So i just bought '07 a6 4.2L S-line and Im curious about the FSI motor. I heard previously that they have a problem with carbon build-up and need to be treated with BG44k at the dealer at intervals to keep it running right. The dealership where I bought the car says theyve never heard such a thing.

I was also curious about the MMI. Ive seen people mention upgrading or updating the MMI version in older cars. What is the advantage to this? Can it damage the system?

Thanks in advance for any advice.