mufflers or no mufflers??

In 1989 my uncle returned home after working in California for sometime. He drove his only car since highschool, a 1967 El Camino with a 283. He had Flowmaster mufflers on it which he bought one night at a dirt track race swap-meet. The guy that sold them to him a couple of years befor he returned home, was the founder, Ray Fuller (I think thats his name).. Keep in mind this was 89 & glasspacks were still the big ticket around here. He had the first pair of flowmaster mufflers in town & probably in Oklahoma to boot! People always stopped & asked him what he had done to it to make it sound like it did!