The engine is mounted longitudinal in the passat but that makes no difference. The difference is that the longitudinal engines using a separate exhaust manifold and turbo, opposed to the complete unit found in the transverse mounted engines. This means you can get an adaptor flange that requires no pokey cast to steel welding.
Darkside do offer a bolt on solution as I'm running it, and personally couldn't recommend forking out that bit extra for the tubular mani, but I know it's out of some people's price range. You get what you pay for though, and the tubular mani'd ones make better numbers and run at nicer temperatures.