The chambered exhaust of the Camaro's in the '60's was probably the prototype of the Flowmasters of today. I worked at a muffler manufacturing shop in the '50's and built a train load of glasspacks, and a few steelpacks. Both have a straight thru core with either louvers (very small ones) or circular punched holes and the casing is stuffed with fiberglass blankets or steel shavings. My personal favorite was a 1953 Chev. 235 with Fenton headers and 18" Porters, wow I can still hear the sound in my mind. I have a muffler I made 50 years ago oval shaped with 2 - 2 1/4"" inlets and 2 - 2 1/4" outlets and stuffed with fiberglass blankets, similar to Jaguar XK120 and XKE's of 1960's. I will run it on my 292 with tubing headers, can hardly wait to hear it when I get it together.
