Exhaust manifold gaskets
i have used expanded graphite on a perforated steel shim 1.5 or 2mm thick
they use it for the "super heated steam" pipes in power generation
good enough for a nuclear power station good enough for my 6 cylinder combined inlet and exhaust gasket. :)
works well good compressibility and seals exceptionally well
but find a supplier who can cut it to your pattern... it will ruin your stanley knife
Dave