If you are going to try the common "nut and bend" method first I would get a coupler nut. It's a long nut. some hardware stores have them or you can get them from McMaster Carr in about 23 hours. I don't know how they deliver so fast. If you are going to heat the manifold cool the stud with water before turning to contract the stud or use freeze spray. You might even hear it crack loose. JMHO.
