C818 For what it is worth, I bought a 1983 RX7 with a bad 12A. I had access to a Mazda factory built marine 13B with a four barrel carb that dynoed at 200hp. I reconfigured for the car and bought Racing Beat exhaust.
The primaries had pre-chambers and twin pipes continued back to the rear muffler which was kind of a Borla copy. The sound was what I described as "titanium bees". It was terrific and not too loud.
jim
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