My racecar has 3.5", X-pipe into Bullets, turndowns dump @ rear axle pointed slightly at each other to help beat a Db rule. Markedly more quiet, seems streetable from a sound aspect. Actually sounds more wicked than open headers, no slower, and I can hear other things in the car. Except at WOT.

Tried the same thing on a racy BB wagon, though, and it was much louder; probably aggravated by the big echo chamber wagons naturally have.