bolts straight on, and I agree put a full GTI system on while you're there! I just did that on its own to my 1.6 and it made a real difference.
If you had a 2e2 you would need to drill the head for the coolant chanel (easy) but since you have a webber its not so important.
The main thing to do if you do this and fit a GTI cam is you need to make a new 6degree BTDC mark on your flywheel, the std carby mark is 18degree BTDC and wont make the best of the shiny new cam.
The haynes has the procedure, use the measurements for the 1.8 GTI EV code engine

I used a snapped off ruler with some tape wrapped round it down the flywheel timing inspection hole, marked it on wi tipex easy peasy
