I recently bought a 2000 S4, it has 71 000 Kilometers on it. What sort of things will be coming up such as timing belt, etc, As well as how often should the synthetic oil be changed?

When i bought the car, the drivers side rear speaker was rattling , it was replaced under warranty but it still sounds like theres a small rattle coming from the speaker, does he bose sound system not have as much bass as i was expecting it to?

How many of you have added an aftermarket sub, and kept the stock head unit.