[Henry Schmidt]

Head studs on air-cooled 911 engine builds is always contentious.
Of course I like Supertec studs and we use them in every build.
Everyone should get to make an informed choice, so my only advise is to use all 24 stud from the same manufacturer. In the case of SCs and Carreras where the top studs are steel, I recommend you replace those as well as the Dilavar lowers. The top studs have unknown mileage and unknown heat cycles so their physical properties will be different from any new stud you install. I've been a champion of the importance of equal champing forces to create the most stable head to cylinder configuration possible.
24 matching studs is your best chance at successes. .