i prefer to do the work myself as its educational, i can learn more about my car aswell as know that im doing a reliable job..
i took my r33 to a mechanic in fyshwick to get a cracked exhaust manifold off when i first bought my car.. he snapped 3 studs inside the head, which is fair enough as they were old and worn.. the thing that got to me the most, was that when he attempted to drill them out, he drilled through the head which resulted in me having oil leaks from the head.. had to call a thread specialist to fix the problem..
after this i started doing all the work myself, and have learned a great deal about my car.. cant trust another mechanic again..