I bought a roll of aluminium foil tape off eBay to tidy up my under bonnet insulator which was looking a bit tatty.
Before applying it, I removed the insulator shield, rubbed in some degreaser (from aerosol), rinsed in heavy rainfall over night, further rinse with hot water then left it to dry for a couple of days.
Here is the finished product after 2 layers:



The photos don't quite do it justice as it is much shinier in reality than it looks in the photos.
There are two different types of clips securing the under bonnet insulator: 91501-S1K-003 (x2) and 91501-SF1-003 (x11). They are all stubborn bar stewards to remove!
I bought some new fixings from Halfords - Trim Panel Buttons (HFX 343) £1.99 for a pack of 12. 13 in total are required but I already had a few spare so didn't need to buy two packs. I cut them in half before fittings 'cos the original Honda clips are shallow and don't stick in very far. These new ones were a bit stiff to put in so I had to use a hammer to knock them in all the way.