Helicoils are the shiz.
Use a tiny bit of loctite when you install them, then some nickel based anti seize on the bolt, so it doesn't gall on the stainless helicoil.
I've repaired three M12 bolts on the super strut suspension in my AE101 (both trailing arms and a mounting plate) when the retards at The Torque Team used a rattle gun to successfully cross thread the bolts.
I fixed it all with helicoils, and they've been there for over a year now and still holding strong.
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