Just tell him to hang out with the allroad folks at Quattroworld. He'll thank you plenty. Just kidding. The thing to get him is a brass T-fitting from Home Depot, believe it or not. It's a 3/8" barbed T-fitting that goes in the hose coming out of the top of the coolant expansion tank. You'll see the plastic one sitting right there in front of the coolant tank. Replace the plastic one with a brass one and he won't ever have to know the agony of being stranded by a $0.30 piece of plastic.
A nice vented oil filler cap will prevent him from having as many oil leaks. That would be a nice addition. Another good small fiddly bit is the lower temperature coolant after-run pump switch. It goes in underneath the expansion tank, down behind the engine. It keeps the turbos from staying hot and coking the oil, austensibly. I think ECS sells the lower temperature version of the switch, which is the one you want.
Of course, perhaps he has bought one that is not a 2.7t, in which case I think all of what I just said might not work out at all.