when I had my 340 with the huge cam and 11:1 compression (cheap headers into walker turbo mufflers, ending in the original tips under the bumper) it was the best sounding car I've ever heard. Amazing.
the way I've always thought about it, is that they sound like the exhaust is falling out the bottom half of the pipe and landing on the ground-sort of backs up the way you describe it as a gurgling sound:D