Here's my evolution in search of the perfect exhaust note, '02 S:
1. Stock, too quiet
2. Had the "pedro mod" done by Fister in SF Bay area: bypass pipes artfully welded into the twin tips ( your "from B to the outlet"). Perfect sound-no drone, deep, fruity, not too loud.
3. Later got a deal on Stebro secondary cat bypass pipes, installed, and holy s**t it got ALOT louder. Some compliments at the autocross, but too "rice" for the street, really loud when you jump on it. I'm not 18...
4. Experimented with sticking pronged 3/4" fuse box plugs ($1.99 at Home Depot) into the tip bypass pipe exits, and voila-the same muted growl as (2) above, with no secondary cats (that passed CA smog BTW)!
Rubber freeze plug nut expanding plugs work too, assuming they don't burn up
YMMV, enjoy! The moral of the story is that the aft cats do most of the muffling.