Early Olds 442's used chambered pipes out the back bumpers instead of resonators at the end of the exhaust system...worked quite well to quiet down the "noise".
I have always thought we could simpley use chambered ovalized pipe to facilitate undercar exhaust clearances, no need for a muffler if the chambered pipe were used....glad to see a commerical source for ovalized pipe posted, now if we could just get them to "chamber" the pipes! I could see that this company might be approachable about the issue
Thanks!
Dugly
