51 plate A4 2.5 TDI air filter change

[Benmac]

Bit of a long shot but here goes.

Mate of mine has just bought himself a very nice 51 plate A4 2.5 diesel. Its a gem, ben looked after from new by an older chap, low miles etc etc. My mate has always replaced his air filters with k&N ones and has bought one for the audi (just the panel replacement not some daft cone filter). He's no mechanic but knows what he's looking at usually and in the past has just done the install himself. However, he's not sure where the airbox is on the A4. I said to bring it to me as its a "5 minute job".

Just wondering now if it is one of those silly jobs that aren't obvious in terms of bits I'll need to dismantle to get at the airbox or if its something as obvious as airboxes usually are. Can anyone offer a bit of guidance?

Thanks