In the early '60s---maybe about '62 or '63, aluminum body-panel Ponchos also came with aluminum 'header' exhaust manifolds. They didn't work very well---too much tendency to melt on the bends. Also, the cars that had them didn't have the rest of the exhaust system, the outlet flanges simply pointed down, and there was an NHRA rule that required the outlets to be away from the body and tires, but not point at the ground. There are probably VERY few of those manifolds left around.
KS