[winders]

This thread says a lot:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/644752-993-head-studs-two-types-3.html

I don't get how you get "Inconsistent clamping force based on environmental changes" with the 993 Turbo dilavar head studs. Dilavar is a metal alloy that expands a certain rate. That rate is more in line with the rest of the engine than other alloys.