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Basically the exhaust heat shield gets eaten away at the fixing points due to corrosion of the metal fixing nut used to secure it to the car & becomes loose, these methods basically give the fixings nuts new materials to hold up & stop the shield rattling. I scraped out all the iron oxide rust and the hole in the heat shield is a circle, like it has always been that size. The heat shield looks in good condition. I've got some washers that will cover it though.Now your ready & can remove the Fixing nut & clean off as much loose material that you can from the heat shield/car. The stud has a screw thread. So after initially pushing the washers on, can rotate them through one of the slots to tighten slightly.

the heat shield now has a big hole in it where originally it had a small hole for the retainer's stud to pass through Simply get your drinks can ( or other material of your choice is similar ) cut out a suitably large piece of metal that will cover the hole in the shield & also plenty of the surrounding shield too.If you have already used method 1 & the rust bug has got hold once more or you just want to only fix the one point with minimal under the car time then this is the method for you. They are a different type of part than the one used on the under bonnet sound proofing, so just buy some, but, be aware that in most cases, the original retainers will still be on the car but rusted up, and the reason that you are finding that the heat shield has fallen down is because it is made of some aluminium alloy kind of material, and these retainers are zinc'd steel - so that has started a reaction that has locally trashed the aluminium alloy material - and it has "gone" and the heat shield now has a big hole in it where originally it had a small hole for the retainer's stud to pass through. So that means that you will need to make up some thin metal disc patches/repair washers to cover these holes when you go to fit new retainers. As for fitment, I guess they just push over the screw stud that is peeping out the heat shield, and has lots of rust on its surface? The heat shield has two little tabs that retain the washer/clip. Bend them down slightly to remove old and fit new.