So do hardened steel bolts.
Stainless is usually fine in high temp situations, as long as the thread is large enough to handle the load, and you use zinc based anti-seize during assembly. I always use stainless studs and copper coated nuts on Stagea dump pipes, but they are M10.
That said, most rear chra housing bolts are hardened mild steel, probably as they handle turbine explosions better.