Torque really isn't all that important in that area. It' not like you're deflecting anything with clamping force. All you're doing is clamping the two flanges tight enough so that the thing layer of RTV can do it's job.
It's way more important to use anti-seeze on exhaust bolts, ESP anything touching the hot side of a turbo.
I want to re-state my concern and reasoning.
A stainless bolt (of a reasonable grade) is nominally harder than a standard (say grade 5-8) steel bolt, but the tensile strength is not higher. That means higher set torque to get the right bolt stretch to maintain torque (not loosen), so you decrease your safety margin to yeilding the bolt. Over torque is just as bad, if not worse, than not enough torque. Given the thermal expansion I would say materials, grades, and fastening torque are pretty important... and will lead to keeping your flat surfaces flat.
That's the theory anyhow, I'm looking for proven methods... to which it sounds like there are no torque values or fastener strengths considered. If so, you're right earl, its not sensative enough to care.
I'm laying out my thought process, because that seems odd to me since I remember my old stock elbow wouldnt seal for crap after I took it off the first time and I didnt consider anything regarding the torque setting or bolt grade back then either.
FWIW... I just thought of another good point: thermal expansion. I dont know how much difference there is in expansion of steel vs stainless, but... since the flange is not cast iron like the factory elbow, maybe the bolts SHOULD be stainless since they will expand at the same rate as the DP flange and tension in the joint would remain pretty close? (also agrees with your logic earl)
Good talk, thanks.
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I'm getting ready to put my new turbo on, and I think the old bolts are looking pretty brittle and crusty.