I have a GTI... there are tons of VW mods out there. Chipping them is harder that some cars (mostly because you really have to pull the engine controller out and get it reprogrammed, you can't just plug in a dongle to get performance).
Here is the most important thing you can know about a VW: It has about 150,000 bushing in the suspension, and each and every one of them will go one after another in a totally random sequence. The parts aren't expensive, but the time to keep getting after them is pretty high. Find a good VW mechanic, and put together a plan to replace the bushing en-mass when you start getting noise from any corner. The front swaybar bushings will go early and often, get use to it.
If it is a 1.8turbo, don't forget that the timing belt and water pump are both due for service at 100,000-140,000kms - a timing belt failure leads to expensive metal pieces wapping each other.
Generally very good cars, good fun, and fast for the price
