I actually said a Tube resonator, which is just a round muffler as opposed to a oval muffler such as a Magnaflow 10435 muffler. you can often fit them the tunnel better than big bulky oval mufflers.
You can do whatever you want, but short of actually sitting down and engineering a system, you're not going to see a big difference in power from one setup to another. it's more about the sound.
Keep in mind I'm speaking from a position where spending $2-3k+ on a hand fabricated, fully Tig'ed, polished food-grade 316ss exhaust is not unusual for my customers.... Not the same as a $300 at a muffler shop job, with mig'ed galvanized. crush-bent tube and generic mufflers, all in. Not that there is anything wrong with that sort of exhaust, just not what we built. A lot of our customers had more money then brains and would buy chrome/polished versions of parts you would never see just to say they had them and spent more money...
When I was seriously looking at doing an exhaust for my LS, I looked at a lot of options from an early merge Y into a 3" single all the way back; duals with both X and H-pipes; and a stock double Y setup. I was also looking at doing a single path, twin 2" with custom mufflers but that was a bit too much for a $3500 car! :P
One option I liked was this:
dual from the cats to a Magnaflow 14385 in the centre section back to dual 14325s in the stock resonator locations back to another set of mufflers at the bumper, possibly another pair of 14325s with turn downs or maybe something with a couple of big VIP style tips...
I've done similar setups on lots of domestic V8s and Big German sleds, they all have sounded really good. Not that typical bark and rasp but a very hard growl with a nice burble on decal... Kind of like a new Quattroporte, but not at the same time. Hard to explain the noise but you'd never be told it sounded bad or was too loud. Also maintained a stock noise level at normal cruising speeds with no drone but definitely had presence when you got on it.
Not cheap though... You're looking at over $700 in just mufflers and thats without tubing or flanges or hangers or tips or install.
you could basically do the above setup and leave the rear mufflers off, run it for a while and then add them in later if you wanted it quieter or mellower...
like i said, you can do whatever you want!