Exhaust. (Replacing rusted studs on catalytic converter)

[aguitarmn]

I'm changing the exhaust from the after the cat and back. Well long story short. The studs coming off of the cat are in bad shape and I planned on just drilling them out and running some new ones but I didn't see until after I had it out that I can't because of room restrictions. That I can't feed new studs through it. So what I plan on doing is drilling them out still and tapping the holes and threading new studs into them. I plan on using locktite (sp?) And hitting it with the welder in a few spots. From eyeballing it it looks like I could get away with some 5/16 studs. But does anyone know what size the actual studs are supposed to be. Thanks.

The cat is in great shape and I do not want to have to buy a new one.

It's a 2008 aveo sedan ls. ATX.