No idea, but I'd bet Turner Motorsport's = ideal
I hear of so many people converting to the TMS wheel studs (from the stock wheel bolts) and I'm sure if there was any kind of hardness or quality issue, it would have been out on the racer forums a while ago. I've been wanting to get a set to use on my street car, just so I don't have to deal with aligning those first couple bolts.
dc