I suspect anything but true duals be a little quieter,I've tried too many combinations I'm tired of this..........LOL
I asked the tech guy at V&H why they didn't test this muffler on a 103 & 110 didn't they think someone besides a 96 rider might want a quiet muffler, dead silence,makes you wonder.
When I first came over to the HD boards, I was surprised how many complained of after market exhausts being loud, when to me, a lot of these exhausts are quite mellow. It's hard to believe anyone would consider my combo (fullsac 2.25" and x pipe) loud, especially compared with a lot of bikes running around there, but I hear of some saying they think even the 1.75 fullsacs are too loud

Of course Vance and Hines are going to make pipes louder than stock- that's the primary reason people want to buy them.... and their Touring mufflers are not nearly as loud as the Big radius, long shots, and others.
I guess noise is in the ear of the beholder, lol, or maybe because I compare everything with my Bub Jug Hugger shorties on my last bike.
Still, when even the mellowest of after market pips are too loud for some, I can't help but to think they might have been better off sticking with their stock exhaust pipes.