Hey sure, The part number of the K&N air filter is: E-1983 (audi S6 or A6 3.0tfsi) Takes 10 mins to fit
also if you wanted to upgrade the airbox
The airbox is from a RS6 (part number 4G0 133 836 AF). Takes 15 mins to fit
out of interest what are you getting mpg wise out of yours? Motorway and town? And is it mapped?