If you are running the cattalitic converters it's really had to duplicate the sounds of the 60's, my friend has a 68 and a 69 Camero with LS motors running short headers with reprogramed computters ( no cattalic converters) with 2 1/2 exhaust and 12" long flat mufflers, they sound pretty good but not as loud as the 60's cherry bomb mufflers.
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