It was a fairly straight forward install. The only things to keep in mind: there are actually eight speaker outs from the monsoon amp. This is a good thing, but it will require cross-overs. We have the wagon (or estate) model, which lead to some interesting things for installing the amp. In the wagon model, the best place to install the amp is in a small cuby-hole on the left hand site of the hatch area. Unfortunately this is a very small space. So we chose the Alpine V Power 5 channel amp. It's a decent quality amp, and with enough power for a sub as well. That's about the only things I know of besides the usual constant versus switched power reversal in Volkswagens. Be sure to tell the installer about that, I have to take mine back.
You'd think VW would standardize on what the rest of the world is doing, eh?