just a general grounding wire.

those bolts look nasty. i have never seen mine i hope they arent as bad.

best thing to do is hit it with pb blaster and wd 40 and soak it in all those sprays and let it sit overnight. if it doesnt work the next day, bust out the hacksaw and set aside a few grueling hours on your back. or find a lift and a plasma cutter and be done with it in 5 minutes. id say its a 95% chance you'll need new bolts. might as well just get a test pipe made, that cat there is a dummy cat which is hollow anyways.