Same here, the header nuts were impossible to git a wrench on all, so, Kroiled manifold bolts last week, and today, zip, off they come....cut the header pipe in two, removed bell housing bolt, take header piece and manifold to workbench.....soon will have brand new cat. and header pipe in place.....can't imagine what the labor charge would have been in a shop......the worst prob. is that a bolt in manifold or cylinderhead would have broken off.....good luck..