Howdy Scotts68:
The system you described in your signature sounds quite adequate for a street type set up. I'm running a similar set up on my 250 engine, except for a Walker Dynomax, mounted all the way back. My engine winds easily to 5 Gs, but that's more a reflection of cam, carb and head work. My brother runs dual on his 200 with a similiarly modified head and dual outlet Clifford headers. Difficult to compare the two due to the size difference, but both work well.
Pros- Single outlet- lighter weight, better heat build up and retention for less condensation accumulation, less cost and maintainance, fewer clearance issues, Usually gives slightly higher torque at low and mid range rpms.
Pros- Dual outlet- High coolness factor, higher hp numbers at higher rpm range.
I doubt that you would notice any difference in performance, given your set up and use, going from a single exhaust to a true dual setup.
That's my two cent, I hope it's worth it.
Adios, David