[Dancake]

Done a repair on one last year using a stainless M8 bolt and some chemical metal. Cut the head off the bolt and cut two grooves in the remaining stud to give the chemical metal something to grab onto. Clean the rust off the car and take it back to bare metal before bonding the new stud to the underside of the car. Leave to set for a couple of hours before priming and painting the area.

You can then use an enlarged washer if the heatshield has rusted away,, making sure to coat it with grease or another suitable rust preventative after securing the heatshield in place. I would advice using a nyloc nut on the stud for added security. It's a cheap and easy fix that should last for years if done correctly.