I think you're right about the compression.
I ran my 367 with three different cams and about the same 180psi cylinder pressure. And it sounded about the same with each combo.
But when I put the smogger-teen in for winter at maybe 130psi, then they were a bit more mellow, until she went to WOT, then the teener was practically quiet compared to the 360. So, it's probably a combination of; the different volume of gasses being processed, and the pressure of those gasses, and the rate at which they are coming thru.
I really liked the mellow-teener at WOT, together with it's moaning TQ carb.
I also liked both of them from 1800 to 3600, in too high a gear (manual trans)and then hammered to just before she breaks loose. As she begins to work, the pipes sing. I think that sweetspot belongs to the pipes, cuz both of them sounded really good in that range.