Just had mine done on a 2.0lt.Was getting the ticking when cold then it progressed to doing it constantly. I started the job myself ,found two sheared studs ,nos 1 and 2 front top and bottom, no thread protruding from head on one so I quickly realised that I would not be able to get into the stud with any drill I have ( very limited space between engine and inner wing)and after being told that one of the studs is VERY close to the water jacket ,I built it back up and gave it to my local (45 miles away ) GM /Opel dealer over here in Ireland.They did them both in a day fitted the modified gasket,correctly welded up the 3 inch crack that was found on the manifold after kindly e mailing me a photo of the unit, flushed out the cooling system and topped up with fresh anti freeze.
Charged me 450 euro which is approx £310.
Interestingly a whirring best described as plastic cogs meshing has disapeared from the engine which was always there since I bought it 12,000 miles ago. It runs turbine smooth now.
HTH's