I've got a pair of large case 2.5" Dynomax Walker mufflers on my '60 NY with 496" stroker engine.
Their sound charactistic, for the most part, is like normal turbo mufflers, they only are a bit louder when the engine is 'working' and they have a nice rumble at idle.
I installed extra resonators behind them because they where just a tad 'too present' for easy driving.