FWIW, I know a lot of people are are thinking they are helping themselves by using stainless studs in a turbine housing, but its really not a great idea. Not dissing ARP fasteners, they make some very nice pieces, which I've used in several applications. 25+ years of experience has taught me that you should plan for component failure. Turbine housing and manifold bolts have a high tendency to seize up, regardless of the material. The issue with stainless is that it's a much harder material, and more brittle than mild steel or chromoly fasteners. Stainless on stainless also seems especially susceptible to galling. Trying to drill/extract a sheared off stainless fastener from a manifold or turbine housing is not my idea of a good time.
At the very least you should chase out your threads with a good quality bottoming tap and use some high temp copper anti seize, something good for at least 1800*F.
Not trying to start any arguments, just my $.02 based on things that I've had to deal with over the years.