Studs instead of bolts are fine but please do NOT run them in until they hit the side of the cylinder and then tighten them "as tight as possible".
You will want to use some high temp Loctite on the threads, screw them in until you have full thread engagement with the exhaust flange, then use a nut against the exhaust flangeto snug the stud tight, let it sit overnight and you are set.</p>