Exorcizamus te, omnis immundus spiritus.
Be gone back to the depths of hell, foul blight of rattle demon.
I did this under the car.
For anyone wanting to get rid of the cat heat shield:
I used a 4" angle grinder to cut the heads off the seized bolts, punched out the remains (pin punch). Bottom piece fell away and the top piece finally came out without dropping the exhaust... well after alot of swearing, heaving and "massaging" the top shell with a long flatblade screwdriver. The key was busting off the spotwelded brackets on the top piece and bending what was left a little. Came out into the wheel arch.