crazy idea

In the '60's Pontiac experimented with aluminum exhaust manifolds on their super stockers. They came with warnings not to run the engine for more than 20 minutes continuously or the manifolds would warp. There are aluminum exhaust manifolds for the marine market, but they have water cooling jackets. Anyone who has monitored a pyrometer on a turbo engine knows the temps can easily exceed 1000 degrees F.
I know an engine run at Bonneville that had EGT probes about 2 inches from the cylinder head routinely saw 1400 degree temps when the tune was right.