Audi Mods - Cheap Parts?

I just wanted to start a thread for places around the UK that sell modded Audi Parts as i can't seem to find many places and the one's i have found don't sell much. The list can contain sellers that sell universal parts but must they must fit Audi's.

Iv been looking for a new 4" backbox, some interior panels which i would like to replace, some new *brighter* headlight bulbs which are E marked (road legal), wiper blades, induction kit, etc. There's so many different parts but i'm having to do alot of research to make sure they will fit my car without throwing a CAN-BUS error like alot of the bulbs will. I also heard that an induction kit would throw an error and i'm not sure about a new backbox. So known sources and parts would be a great help to myself and other members.