They would NEED to be made out of ALUMINUM. Otherwise it would be like bolting another cylinder block to the front of your car
IIRC some max wedge exhaust manifolds were made out of aluminum for NASCAR use but didn't fare well if I recall
I believe Pontiac also played with Aluminum exhaust manifolds on the big oval as well?
The 421 Pontiac aluminum exhaust manifolds were recommended for drag racing only. Pontiac also had stainless steel headers and cast iron manifolds for longer duration racing.
July 19th should be "Drive Like Rockford Day". R.I.P. Jimmie.
