I put the install in a mechanic's hands, but he said he couldn't/wouldn't do it because the rear manifold's studs are near their breaking point. to remove them, he said it would be a pain in the ***, and he doesn't have the tool to drill them out. so he gave it back to me, and didn't install it

so what's the proper way to install this thing and work around/fix the weak studs?

Budget Y Pipe, 98 Cali Spec

Take out the old studs, retap and install new studs?

go to a mechanic with better tools.