Removing stock exhaust manifolds

It helps to heat the bolts/nuts with a torch (propane and propane accessories is ok).

Lots-o-penetrating oil...

Then turn them to tighten them at first to break them loose.

After you feel it break loose, then reverse and loosen.

I find that heat is the most beneficial on old rusty nuts and bolts...

Remember the tip of the cone in the flame is the hottest point (the inner one)....