Using a single muffler with dual outlets was the option he spoke of that
sounded bad. I'm thinking surely there is a muffler out there
manufactured by someone for the v-10 application. Hope so
anyway.........

The shop wouldn't even consider straight duals because of the legalities
surrounding the cat converter.

A BIG one.  My local guy has done a bunch of V10s here in the area,
but he doesn't do duals.  He replumbs the exhaust from the manifolds
back with 3" pipe and builds a custom "Y" pipe to join the two
manifolds up right before the Cat.  He adds a high performance cat and
a big flowmaster before dmping the exhaust out at the original
location.  He says there's no way to get a decent sound out of the V10
and you'll never get a good rumble like out of a V8.  (I wonder how
Dodge got the Viper to sound like that?)  I've considered the change
on my '02 for quite a while, but something else always comes up that
eats into my "truck/toy" budget.  hehe

I know people who have done the Banks Power Pack with their torque
tube manifolds (headers) on  V10s and it doesn't rumble.  I know a guy
with a Kenne Bell supercharger and the JBA shorty headers on his with
3" duals/Flowmasters and it doesn't rumble.  Another with a Paxton
centrigugal supercharger and the 3" setup above and it doesn't rumble.

Assuming 2000 RPM at cruise, a V8 would produce about 266 exhaust
pulses per second
A V10 at the same speed would produce aboiut 333 per second.

Single or dual the exhaust pulses would be the same so the pitch of
the V10's exhaust note would be higher in any case.

Personally, I'm looking for better flow than a "cool" exhaust tone.
I'd opt for whatever gave me the best performance.