I have heard several inline 6’s with dual glasspacks attached to headers with the tubes evenly spaced in the firing order. All had mufflers mid-car with substantial tailpipes to drop the dB’s a bit. It makes an exceptionally sweet sound, IMHO. Kind of a “ripping cloth” sound as revs build.
V12’s just double the frequency - 2 sixes married together. That’s why Ferrari likes V12’s so much, I’d guess.
My 90 degree V6 odd-fire could never create that sound and, oh, how I tried! It actually sounded a bit like a Corvair flat 6.