are shumacker headers restrictive?

cudaboy 67 said

are shumacker headers restrictive? got some on my 68 440ci, pal says they restrictive and he could make better flowing ones :bootysha: blah blah reason went with these as allow b/b without cutting the fenderwells, cheers!

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I run them on my Scamp with a 440. The fastest I have had my car down the track with mufflers and a set of M/T Pro-Sportman tires was 12.01@112 MPH. The car was still spinning off the line. I would say thats not to restritive, but it may go faster with a set of TTI's. I am not changing mine at all.