There are a million ways to extract a stud.

Do you have a welder? Do you have room to put 2 nuts on it?

The steel stud is in an aluminum head, and you can take advantage of the relatively low temperature at which steel/iron (except stainless) melts and oxidizes. I've heard of (but only secondhand) people using an oxy-acetylene torch to melt out a stud.

Other options are using a mig welder and a nut and adding enough material to bond them together. There's also something called EDM (not techno hehe) that uses sparks to erode studs much the same way that spark plug arms wear away.

Last but not least is heat and penetrant and wrenches.

I'd love a welder especially for things like this. The heat and electric current running through the stud and its threads can loosen and disrupt corrosion holding the two together.

Good luck! And no e-z outs! They're a great way to have to farm out work to a shop.