What can be retro fitted at a later date?

[Schizophonic]

Money was a bit tight when I brought my car. I know the A3 has loads of optional extra but I want to know what are my options if I go for retrofitting something like Xenons, QVGA screen, etc.

Can they be done?

 

[NHN]

Yes systems can be fitted, as long as audi havnt locked us out or wont let the cars systems be updated to cater for the retrofitted systems.