Also with a gt15 turbo I don't think you could make enough boost to have head gasket issues. Maybe, but if you do it would be at that point I would put the studs in. If you go with a larger turbo capable of more than 20lbs/min I would look for some studs, but from what I have seen even the .48a/r 60 trim gt15 makes maybe 20lbs/min. So the stock one for VW should be way ok for the factory bolts.
As stated, it will never hurt to add them. I was just trying to offer you a solution if cost was an issue.