I have not seen may people who have done this mod and there seems to be no guides around on how do do this easy mod. The FSi had an oil filler neck extension as standard so that it works with the standard airbox, but when you fit an aftermarket filter, the neck just stands out and looks pants. The good thing is that the neck can be removed and the oil cap just fits in its place.
I dont have any pics of the process, but it just breaks off. I use a nice chunky set of pliers and give the neck a little twist.
Before:
After:
Much Better
Alex