Steve,
At the 2015 Concours Italiano, I noticed a very nice Pantera with 180's. When it started-up, it sounded great but I remember being surprised that it wasn't louder. The owner told me the mufflers were Borla XR1 Multicore Racing mufflers. Rather than having one length of perforated tubing inside the muffler, Borla's multicore units split the flow into 3 or 4 lengths of 1" perforated tubing. They also use stainless steel packing material, so they don't burn out. If I recall, the Pantera had 3" mufflers not 4".
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