Exhaust manifold bolt holes stripped

[Nostalgic]

Echoing most of what Rawze said, and adding that Timesert kits come with the drill bit, chamfer bit, tap and inserts to do it correctly. I will add that I have no experience putting in helicoils personally, I've always used Timeserts, but I have tore down stuff and found helicoils. Sometimes they're good, and others....it depends on the installer.