I made three different heat shield versions last year and my last version was long like the one shown in the picture. It did help keep the heat off of the bowls while at idle speeds and after the engine was shut off. I know the idea works and now I want to buy one for a permanent setup. I like the idea of having the layers of aluminum with the other material in between them. The aluminum would make the piece stiff enough and not crack while the other material will help with heat transfer.

Thanks for your response.