dude just cut it as close as possible to the manifold and weld it shut. I would suggest getting a another circle piece and welding around the seem to close it. dont stick a bolt in it.
dude honestly if that emissions shits goes on you know how many cars will be off the road completely. im sure once its been passed, which I doubt you'll probably have enough time to fix it. back on topic.....Cut that bitch and weld.