Friend of mine spotted what he reckons is a combustion problem on my 2.0FSI [done only 6200 miles]. He saw very black carbon "stripes" leading from the lower edges of both tail pipe lips, back along their undersides and sort of joining up on the underside of the box. He said the inside of the tail pipes are far too sooty and the stripes are condensation running back and depositing carbon. He reckons it shouldn't look like that and could screw up the catalyst sensor and put on an engine warning light soon. Any comments? Should it be checked out?

No; get him checked out

Sounds normal to me, your friend however does not.

That's a relief! Phoned my local dealer and he said they'd have a quick squint at it early next week, just for reassurance.