Someday I want to run headers and dual exhaust. (a cam and sniper efi too) 64.5 coupe with 170 I6. Daily driver in good condition. I'm not in a hurry. I can hit the bolts with PB blaster every day for awhile before I ever put a wrench to them. What are the chances they'd come out without breaking ? 80k miles on the car, manifold has probably never been off. Would heat help ?