^ not exactly. They aren't crappy and they reflect radiant heat up to like 90something% efficiency. As in they make excellent heat barriers. Do you know who Gordon Murray is? He seems to disagree with you as well. Respectfully of course.
You're not meant to wrap your engine with it, you're meant to use it to isolate components that will work more efficiently (or at all for that matter) from radiant heat. Things like cam sensors, intercooler piping, firewalls, etc. can benefit from gold foil covering.
I don't think JDM stickers work better than the gold foil used on the McLaren F1 for example....definitely not bling haha
