Hello everybody, im from Europe-Slovenia, so i can give you a little information about vw diesels. For the first thing, forget about transplant, you have far more superior engine in your subaru than vw has. Diesel engines are heavy as hell (built from iron). They do have a lot of torque, but in a very limited rev range (1500-3500). If you´d like to stick it in you would have to modify the whole car, replace the fuel pump, fuel lines,... Bottom line it doesent pay off. People here buy diesels mostly because of the expansive fuel.
If you want to know anything else just ask. (sorry if my english is a little ˝rough˝)