all of the above google muffler cut aways of flowmaster, magnaflow, gibson and others... inlet corrasponds to the size of the pipe your mating the muffler up to from your cat... some mufflers have flow through designs, some have little baffels in them to make them quieter but creats more backpressure and so on
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Agreed...it's for placement and routing given any restrictions based on the vehicle configuration. Also, a single in / dual out gives you the flexibility to run two tailpipes with one muffler if you can't run true duals.
I was wondering the same thing. You would think a C/C would have less restriction than one with any offset as it has more of a straight through design. I can't imagine the sound would be much different.