Thinking outside the box
It's a combination of factors not at all related to the materials or design. NHRA does have issues with factoring... Not just mopars, but certain models of all the manufacturers seems to get factored oddly. Second, simple numbers... Economy of scale. A low production mopar is less than 1000. A low production Chevy is less than 10,000. There are 10 tiems as many guys figuring out how to make a Chevy run perfectly, and exceed it's design. So it's natural that the record books will show more performance gains by them.