Can't give you the answer that you probably want, but here goes; I'm having good luck w/ Bosch in my SC, using recomended plugs, a LOT of Porsche mechanics like NGKs, however, in 911s.
It would be hard to say which is better unless someone actually ran both and had problems w/ one and not the other. I'm curious to see if any mechanics or shop owners chime in here w/ some semi-scientific results.
